SERI/TP-234-1923 UC Category: 61a (Biomass Energy Systems) Fundamental Pyrolysis Studies Thomas A. Milne Robert J. Evans Michael N. Soltys March 1983 To be presented at the 15th Biomass Thermochemical Conversion Contractors Review Meeting Atlanta, Georgia 16-17 March 1983 Prepared Under Task No. 1303.00/1572.00 WPA No. 876 Contract No. B-C5848-A-Q/B-F0409-A-Q Solar Energy Research Institute A Division of Midwest Research Institute 1617 Cole Boulevard Golden, Colorado 80401 Prepared for the U.S. Department of Energy Contract No. EG-77-C-01-4042 Previous Reports in this Series: SERI/TP-622-1139 SERI/PR-234-1537 SERI/TP-622-1152 SERI/PR-234-1617 SEA 1/PR-622-1347 SEA 1/PR-234-1665 SERI/PR-234-1454 SERI/PR-234-1884
Solar Energy Research Institute A Division of Midwest Research Institute
1617 Cole Boulevard
Golden, Colorado 80401
Prepared for the
U.S. Department of Energy Contract No. EG-77-C-01-4042
Previous Reports in this Series:
SERI/TP-622-1139 SERI/PR-234-1537
SERI/TP-622-1152 SERI/PR-234-1617
SEA 1/PR-622-1347 SEA 1/PR-234-1665
SERI/PR-234-1454 SERI/PR-234-1884
NOTICE This report was prepared as a� account of work sponsored by the United States Government. Neither the United States nor the United States Department of Energy, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, product or process disclosed, or represents that its use would not infringe privately owned rights.
•
ABSTRACT
FUNDAMENTAL PYROLYS IS STUDIES
Thomas A. Milne Robert J . Evans
Michael N . Sol tys
Solar Energy Res earch Ins t itut e 1 6 17 Col e Boul evard , Golden , Colorado 80401
Progress on the direct mass spectrometric sampl ing of pyrolysis
products from wood and its constituents is described for the period
frm June , 1 98 2 to February , 1983. A brief summary , and references to
detailed report s , of the qual itative demonstration of our approach to
the study of the separated processes of primary and secondary
pyrolysis is present ed . Improvements and additions to the pyrolys i s
and data acquisition systems are discuss ed and typical resul t s
shown . Chief of these are a hea t ed -grid pyrolys is sys tem for
controll ed primary pyrolysis and a sheathed -flame arrangement for
s econdary cracking s t udi e s . Qual itat ive resul ts of the secondary
cracking of cellul os e, lignin, and wood are shown as are comparisons
with the literature for the pyrolysis spectra of cellulos e, l ignin,
and l evogl ucosan . "Fingerprints " for a number of material s are
shown, with spectra taken under carefully controll ed conditions so
that sensitivity calibrations for different compounds , now being
determined, can be applied .
INTRODUCTION
The goal of these studi es is to determine , in mol ecular detail ,
the chemistry and kinetics of the primary and s econdary pyrolys is
processes for biomass and its cons tituents . To accompl ish this under
realistic pyrolysis conditions , we are coupl ing s everal pyrolysis
heat transfer methods with a sampl ing sys tem -mas s spec tromet er
detector that permits real -time sampling and rapid quenching from
ambient hot environments , whil e preserving reactive and condens ibl e
1
species for nearly universal det ect ion by pos itive -ion mas s
spectroscopy.
Work in FY8 2 on the sys tem and its qual itative performance has
been described in two quarterly reports(l, 2 ) and a paper pres ented
at the 14th Biomass Thermochemical Contractor's Review Meeting(J) .
An overall review of progress to dat e is contained in two papers
accep t ed for publ ication in the Journal of Anal ytical and Appl ied
Pyrolysis<4, S) and a paper prepared for the International Symposium
on Fundamentals of Thermochemical Biomass Convers ion<6 , 7> .
These publications pres ent a weal th of detail on the des ign and
qualitative p erformance of the pyrolysis and detect ion systems , with
the conclusion that the chosen approach is well -suited to provid e
unique information about the details of pyrolysis under extreme
conditions of rapid h eating and unusual environment s . Primary and
s econdary reactions can be followed over the temp erature range from
low t emperature to 3000°C , on the millisecond t ime scal e . Pulse d
pyrolysis can b e carried out with samples i n the 1 -10 mg range as
well as with much larger s ampl es . Heating schemes us ed to dat e
include the burnt -gas region of Ar -H2 -o2 or He -H2 -o2 flames ;
Cal -rod• -heated inert gas es ( Ar, He, others if desired) ; and
resistance heated grids . The sampl ing sys tem is quite well suited to
coupling with radiation -heated surfaces (las e r, solar collectors ,
arc) but these are not yet availabl e in our laboratory .
In the period since the las t report ( 3 ) , we have cl eaned and mad e
changes in the sys tems , and developed several techniques , all in
preparation for the current phase of quantitat ive s tudi es . Thi s
report describes these activities , a few result s of parametric stud
i es on cel lulos e, l ignin and wood, and the firs t results from the
appl icat ion of several new techniques . A compl ementary study of the
detail ed organic mechanisms of cellulose pyrolys is is being carried
out , using the same apparatus and techniques ( 8 ) and funded by the
SERI Director's Discretionary Fund. This s t udy permits us to conc en
trate now on the quant itative mechanism of secondary pyrol ysis of
primary products from cellulos e, l ignin and wood .
2
SERI 8 3 0 A 0 1
Resul ts from the new work , where they provide information of
direct rel evance to exis ting studies , will be report ed in this and
subsequent progress reports. In the following sections we review
instrumental development s foll owed by a discussion of recent
experimental results and a comparison with the l iterature . The final
section outlines planned s tudies for the remainder of FY 1983.
SYSTEM READINES S
Sys t em Cleaning
The free-jet sampl er -mass spectrome t er detection sys tem, shown
for reference in Fig . 1, had fal l en into s ignificant disrepair after
a year and a half of steady us e wi th a variety of hydrocarbons and
biomass material s . The chief problem was a cumulat ively mass ive
increase in background contamination of the ion source and
turbomol ecular pump regions, s uch that even the phase -s ens it ive
detect ion was hampered by unfavorabl e s ignal -to -nois e ratios at
certain masses. (This effect can be s een as pos itive -negat ive
excursions on some of the mass spec tra shown below . Noi s e is
particularly bad in the vicinity of mass es 47, 70, 80, and 1 1 0.)
This contamination became worse the longer either the turbomol ecular
pump or the mas s spectrometer ion source were operat ed so that,
finally, only about two hours of operating time were usabl e each
day . Two sources of contamination were identified: oil from the
turbomolecular pump that unaccountably backed up into the entire
s tage three chamber ( see Fig . 1 ) and the expected long -term
accumul ation of pyrolysis tars and oils from the hundreds of samples
inhaled through the molecular beam inl e t .
In mid -August the sys t em was compl etely disass embl ed for the
following actions : a) a thorough vapor -degreasing of s tage -three and
the partially disassembled mass spec trome ter ; b ) a thorough overhaul
of the turbomol ecular pump, with bearing replac ement and subs ti tution
of a new, higher qual ity oil (Fombl in) ; c ) sol vent cleaning of the
Edwards boos ter diffusion pump, promp t ed by the rather dirty state of
the oil ; d) a liquid N2 trap was interposed between the
turbomol ecular pump and the stage three cros s . The sys t em was back
3
Stage 3 Pump
Stage 2 Pump
Stage 1 Pump
ampling Orifice
Burner ----1
Figure 1. Molecular Beam Apparatus for Fast Biomass Pyrolysis
4
in operation by mid -October , and showed a remarkabl e decreas e in
background l evels of about two orders of magnitud e . Furthermore, the
system becomes cl eaner with operation through the day , due to sel f
baking of the ion -sourc e .
Mass Spec tromet er Sys t em Improvements
Three changes were made in the bas ic mass spectrometer syst em .
Firs t , the tungs ten f ilament was replaced by a thoriated iridium
filament , which operates at lower temp erature and is more resis tant
to burnout . S econd, a pre -amplifier, ion -c ounting package was added
to permi t direct ion counting . This capabili ty is part icularly use -
ful for weak signals and for fas t t ime respons e . As an example of
the latter , the signature of a chopped , intense argon beam is dis -
pl ayed in Fig . 2 . The chopping frequency is 1000 Hz and the time
response is at the �s econd or fas ter l evel . (The anomalous p eaks and
tails on what should b e an essential ly square wave probably represent
a mul tiplier response effect caus ed by the intense ion beam from
argon. )
:Figure 2. Chopped Mo1ecular -Beam lave :Formed by Fast -Response, Direct Ion -counting .
5
A third addition to the mass spectromet er sys tem is a
1 6 -channel, digitally controll ed, peak switching system that all ows
the sequential monitoring of up to 16 ions during a pyrol ysis
even t . Being des igned, but not yet rec eived, i s a computer -bas ed
data acquisition sys tem to record and process compl ete mass spec tra
as output from our phase -sens it ive ampl ifier . Such a system will b e
needed a s we enter the systematic, quantitative phas e of work . Al so
ayailabl e, but not yet test ed, are the el ectronics to extend our mas s
range to 1500 amu to screen for very heavy oil s and tars and an MS/MS
sys t em to enhance our ion identification abil iti es .
Syst em For Quanti tat ive Secondary Cracking Studies
In order to s tudy the s econdary cracking of the primary tars and
oils obs erved from cel lulos e, l ignin and wood, we l).ave improved the
flame sys tem in several res p ee ts . Fig . 3 shows the new specimen
holder and quartz spacers designed to confine the flame gases and
prevent encroachment of surrounding air . The wire hol ders, for sol id
specimens l ike wood splints or rol l ed filt er paper or for small boats
for powders , are shown with spacings to hol d a three -specimen array
in a 2 -em x 2 -em area. Such arrays will give higher pyrolys is vapor
concentrations and will allow tests to be made of the importance of
diffusion of vapors at extended s econdary cracking dis tances .
Previous tests have es tabl ished that there is littl e cooling of the
quartz -confined fl ame gas es, at l east over distances of 100 em. To
obs erve s econdary cracking as a function of dis tanc e the upper quartz
cylinders are varied ( e . g . , 1 0, 20 , 40 , 80 mm) and the s ampling cone
is at or below the exit gas pl ane .
are shown bel ow .
Heat ed -Grid System
Firs t resul ts with this system
The wire -mesh, resis tance heated sys t em, for forced, rapid
heating of powders and thin specimens, was described earlier< 3 ) .
This system, pat terned clos el y af ter thos e used by the MIT group for
coal and biomass studies C9), has been tested both electrically and
with the sampl ing system. Figures 4 and 5 show the heated -grid
arrangement and the_ housing and sampling orifice plate arrangement .
6
Figure 3. Photo of Sheathed Burner and New Sample Holder
In the prel iminary experiments shown below, the grid was driven by
the analog control uni t , with no feedback control . In this mode , the
control unit calls for a certain current as a step function, and for
the same or a different current as a holding current , for a sel ect ed
time. The heat�p rat e in this mode of operation is det ermined by a
combination of the time -cons tant of the Vec trol• and the heat
capaci ty of the grid sys t em. An Appl e computer, thermocoupl e
feedback sys t em is operational for clos ely controlling the actual
heat�p and hol ding profil e when desired .
PRIMARY PYROLYS IS STUDIES
During the pas t year we have developed an operational set of
parameters to permit both integrated scans over the entire pyrolys is
wave and to obs erve the s equential evolution of up to 16 peaks
through a pyrolys is event. Wi th the sampling sys t em placed at a few
to 10 mm above the pyrolyzing surface , largely primary events are
observed, even in surrounding 900°C steam/argon .
7
Figure 4 . Photo of Grid Structure
Figure 5. Assembly Photo of Heated Grid SysteJR
8
The data acquis ition and s ensitivi ty charact eris tics are such
that we are limited to 400 amu scans at a one -second repet ition rat e
(with some loss i n resolution ) . More frequent scans can b e used over
smaller mas s ranges in a reciprocal trade -off ( e . g. , 40 amu int ervals
could be scanned in 0.1 sec ) . Single -ion monitoring can be used to
foll ow changes on the millis econd t ime seal e, limited only by the
time respons e of the phase -locked amplifier (present frequency of
beam chopping is 1000Hz). We have s till not developed an optimum tuning for our quadrupole
mass spectrometer to achi eve both workabl e resolution and sensitivity
and to fai thfully transmit bo th heavy and light ions (e.g . , 16+ from
methane and 162+ from levoglucosan) . In much of the data shown
below, tuning was for high -mass transmi ss ion in the 60-220 mass
rang e, with large discrimination against light gas es. It is likely
that two sets of experiments will have to be performed to quanti ta
tively assess both h igh and low mol ecul ar -weight pyrolysis produc t
behavior. Examples of the quality of spectra now being obtained are
seen in the experiments described bel ow.
Cellulose--Dep endence on Several Parameters
In the quantitat ive s tudy of the pyrolys is of cellulose, the
initial question was whether the pyrolys is mass spectrum depended
s trongly on the type of cellulose, its physical form, the degree of
crys tallinity and polymerization, t emperatur e, ionizing electron
energy, quantity of sample, heat ing environment, and impuri ties . A
large number of spectra were taken for cellulos e under a variety o f
conditions , as report ed i n earlier progres s reports (1-J). The gen
eral conclusion, though we did not have cel lulose s ampl es precisely
charac teriz ed as to degree of crys tallinity, degree of polymerization
and nature of impurities, is tha t, for the heavier tars and oils at
least, the primary product sla t es are qui t e similar over the range of
parameters s tudied. As exampl es, Figs. 6-11 compar e spectra (heavy
masses emphas iz ed) for : five types of cellulos e at bo th high and low
el ectron energy ( Figs. 6 and 7 ) ; small vs. large spec imens ( Fig . 8 ) ;
temp erature of gaseous pyrolys is medium ( Fig. 9) ; He vs. Ar as flame
9
� l� Ul4U�-----·
. ·�-- . 18 �0
. .
98 144
� ...
( e ) 8
( d )
( c )
(b )
( a )
Figure 6. Primary Pyrolysis Mass Spectra of Five Different Specimens Heated in 900°C �/o2Ar Flame Gases; Electron Energy 50 eV . (a ) fil t er paper (thin sheet ); (b) cotton thread ; ( c ) Sigma chemical amorphous powder ; ( d ) Avi_cel crys tall ine powder, 90l-!; and ( e ) Avicel crys tal l ine powder, 20l-! ( powders heated in smal l boa ts ) .
Figure 7. Primary Pyrolysis Mass Spectra of Five Different Specimens Heated in 900°C 82/02/Ar Flame Gases; Electron Energy -17 eV . (a) fil t er paper ( thin sheet ) ; (b) cotton thread; (c) Sigma chemical amorphous powder ; (d) Avicel crystall ine powder , 90�; and ( e ) Avicel crys talline powder, 20� (powders heated in small boats ) .
11
I, l I! (I ! I } ! , . I i I·! I
i . I ! .
,I I i I ., l·v � :1\ .I . I ! � I '\ , '
I ' , I I , :, ' I U\j\/J
I
UWJ\J
6'o a·s
Figure 8. Comparison of 50 eV Spectra of Small (-17 mg) and Large (-)100 mg) Rolls of Filter Paper in 900�C Steam/Argon. Lower spectrum is for small spec imen.
Figure 12. Pyrolysis Profiles from Cellulose (60+) Heated in Be/B2/o2 and Ar/H2o2 Flames of the Same Temperature . The hel ium fl ame profil e is on the l ef t .
16
For the purposes of es tabl ishing the detail s of primary
pyrolys is the diff erenc es shown in Figs . 6 -1 1 may have s ignificanc e
and will be examined further in the work supported by the Director's
discretionary funds <8) . To s tudy the pathways and conditions for
optimum yields of secondary products from primary tars and oil s , the
choice of cellulos e form (as long as it is quit e pur e) would appear
to be a matter of experimental convenience . The firs t quantitat ive
studies of s econdary cracking will probably use rolled s trips of ash
free fil t er paper ( Whatman #40 ) .
Cel l ulos e and Lignin Spectra - -Comparison with Literatur e
Two comparisons of our prel iminary spectra with l iterature data
are pos s ibl e . First is a comparison of the types of ion peaks
observed with prior chemical identification of tars and oil s . In a
previous report (ll) , identificat ion of ions with precursors widely
reported by others showed the reasonabl eness of the species observed
under our conditions . Prominent in the suspec t ed cellulose products
and hydroxy acetadehyde (60+) and methanol ( 3 2+) . Prominent in
l ignin spectra are three s eries of ions ; 94 , 1 08 , 1 2 2 , 136 , 1 5 0 , 1 6 4 ,
178 • • • for alkyl phenols; 124 , 138 , 15 2 , 164 , 180 for
monomethoxy phenols and 154 , 1 68 , 182 , 196 , 2 1 0 • • • for dimethoxy
phenol s . Dihydroxy benz ene at 1 1 0 is another identificat ion . lobod
(see below) shows peaks consonant with cel lulose and l igni n, plus two
p eaks , 9 6+ and 114+ , expected from the report ed hemicellulose
pyrolysis product s 2 -furaldehyde and 3 -hydroxy-2 , 2 -penteno -
1 , 5 -lactone , respectively ( 1 2 ) .
A s econd comparison is with the spectra reported in the
analytical pyrolysis l it eratur e, where the heating of micrograms of
mat erial in high vacuum at temp erature below 600°C is common . Such a
comparison is shown for s everal l i t erature spectra <13 -1 7 ) in
Fig . 13 . A discussion was given in a previous report ( 2 ) • The most
striking f eature of Fig . 13 is the relat ive lack of high-mass ions in
1 7
90 t
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CELLULOSE
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MASS AXIS, M/Z
1!26!144 (b)
: I
1, .. ( a)
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I 162 I
'" r1RS3 AY:S. ""/Z
Figure 13a . A Comparison of Cellulose Pyrolysis Spectra. (a ) Fil t er paper pyro lyzed in 900°C fl ame , l ow voltage el ectron impact ( SERI ) . (b) F i el d ionizat ion spectra of glycogen by Schul t en and Gortz [1 4] ( s tated to be ident ical to cellulose spec trum) . ( c ) Chemical ionizat ion spec trum CH4 ( Hileman et al ) [15]. (d) Las erinduced pyrolys i s , electron impact ( Lincoln) [1 7].
18
'"
!0ilr
,. ,
9
0 � ,.I ••I
101
CELLULOSE
CEL!..ULOSE
·j 59
" "
II I,.
200 25il MASS AXIS, M/Z
Ill I I !I )!,1111 T I ilj ,, lllil !SZ
CELLULOSE
sa7J
150 200 250
MRSS RxiS. M/i'
150 200
"'R55 RY!S, r•vz
,.
� ( c ) g
(b)
( a)
Figure 13b . A Comparison of Cellulose Pyrolysis Spectra. (a) Fil ter paper pyrolyzed in 9 0 0°C Fl ame. Low voltage el ectron impact ( SERI ) . (b ) Curie point pyrolys is . Low voltage el ectron impact (Meuzelaar) [1 3]. (c) Direct ins ert ion probe spectra, high vol tage electron impact (Frankl in) [1 6].
19
conventional analytical spectra and the general conformity of our
spectra with the fiel d desorption spectra of Schult en<1 4) . There are
ways to explain the relative lack of heavy ions in the conventional
pyrolys is spectra. These could include dif f erent tuning of the mass
sp ectrometer; loss of less volatil e components in the indirect inl ets
of mos t Curie -point and pyroprobe sys t ems ; mass s eparation of heavy
ions in our syst em (f irst power of mol ecular weight enhancement of
neutral speci es ) ; pyrolys is under high -vacuum versus high -pressure
pyrolysis ; and temp erature dependence of fragmentation pat t erns .
( Our syst em and fiel d -desorption probably achieve ionization with th e
l eas t int ernal energy contribution to fragmentation with the
exception of chemical ionization us ing gas es such as NH3. ) The
detail s of the ionization behavior of primary pyrolysis products will
be a subject of future s tudy. For now we conclude tha t our sys t em
can yield a rich spectrum of heavy , primary products capabl e of
quantification for mechanistic s tudie s.
Figure 14 shows a more limit ed comparison of lignin
spectra<18 -20) . One makes the same observations as for cellul os e ,
with the caution that "lignin" i s a much mor e variabl e material than
cel lulos e . Our res ults agree qui t e satisfactorily wi th fiel d
ionization resul t s of Schul ten<20) using the same sampl e of ethanol
extracted, s t eam -exploded, aspen 1ignin<2 1 ) .
Cellulose Pyrolysis in Hea ted Grids
The heated grid system shown in Figs . 4 and 5 has been tes ted
initial ly with small strips of Whatman 1!40 filter pape r. Pieces
25 x 8 x 0 . 2 -mm thick , weighing about 17 mg are sandwiched between
l ayers of 325 mesh s tainl ess s teel. The mesh is pos it ioned about
5 mm from the sampl ing orifice. The chamber is filled with one
atmosphere of gently fl owing argon which is shut off jus t before
heat ing the grid to minimi z e cross draf ts. Figure 15 shows singl e
ion monitoring of mas s 6 0+ at three different final grid t emperatures
(about 580 , 660 , and 890°C , respect ively ) . The hol ding time at
t emperature is 20 s econds , but the primary pyrolys is is cl early over
in a fraction of that time. (For comparison, a 60+ emi s s ion profil e
20
100:
10B r
oel
f
e
'
f
I f
i :03
HHEAT STRAW UGNHJ
STRAW LIGNIN
lOTECH L!:GmN
!OTECH �IGNIN
55 1'2
,. I '"
i 11
1J!IIS4
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i "'
!I , ..
I II m
I 302 I lr i I I I
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MASS AXIS, M/Z
( e)
(d)
(c)
(b)
( a )
"'
na�2 j JEIS
I I ';'I i i i '
i I ! ! 1 1 I ! I l
Figure 14 . A Comparison of Some Lignin Pyrolysis Mass Spectra . (a) St eam-exploded aspen l ignin powder pyro lyzed in 900°C fl ame . Low-voltage el ectron impact ( SERI). (b) Steam-exploded as pen lignin. Field ionization ( Schulten) [2 0]. (c) Straw l ignin. Curie point pyrolysis . El ectron impact (Haider) [18] . (d) Wheat straw lignin. Curie point pyrolys is . Electron impac t . (Meuzelaar e t al . ) [l9] .
� 1 s
Figure 15. Pyrolysis Profiles for 60 from Cellulose (Filter Paper Strip), Captured in Heated-Grid . Sampl e s iz e 2 5 x 8 em x 0 . 2 mm. One atmosphere col d argon . Orific e 5 mm from mesh top surface . Three heating l evels . Full power achieved in 1 s . Approximat e peak t emperatures are 890, 6 60 , and 580°C and temperature holding t ime is 20 s .
from a 1 7 -mg roll of filter paper in the 9 0 0°C fl ame gas es pers i s t s
for about 10 seconds . ) I t is apparent that the heated grid permi ts
forced heating at cons iderably greater rates than from convective
heating in the flame gas es used to dat e . Figure 1 6 shows a compl ete
spec t rum of cel lulos e from the heated grid operated at the l owe s t
temp erature condit ions shown i n Fig . 15 . The f eatures o f the spectra
are quite s imilar to the spectra in hot fl ame gas e s , even though the
primary products emerge into cold , surrounding argon . ( Of cours e,
some heating of the argon in the vicinity of the hot grid mus t
occur . ) It is gratifying to obs erve that immediate condensation of
heavy mat erials does not s eem to occur jus t above the grid prior to
extract ive sampling . The chamber -does fill with "smoke , " however ,
shortly after the grid is heat e d . Some of this material eventual ly
finds its way into the pyrolysis gases sampl ed at times longer than
Figure 16. Spectrum of Cellulose at Conditions Shown in Fig. 15. 200 amu . 18 eV .
the Lowest Temperature Sixt een 1 -s scans from 5 -
Time Dependence of Cell ul o s e Primary Produc ts
The recently acquired , digitally programmed , 16 -peak switching
device for the Extranucl ear'" mass spectrometer has been tested wi th
c ellulose in hot flame gas pyrolysis . The system permi ts s equent ial
switching between 16 preselected masses with dwell times as short as
5 ms . Figure 17 shows the time dependenc e of a number of masses
during the pyrolys is of a 1 7 mg roll of f il t er paper in 900°C steam -
argon . In this ins tance one of us [8] has directly interfac ed the
peak -switched output of the multichannel analyzer wi th an HP 9845
computer for data storage , manipulation , and pl otting. Not eworthy in
Fig . 17 is the perhaps compl ete conformi ty in the emission of
products leading to the major heavy masses being monitored . Two
explanations ar e : that all the ions are ionization fragments of one
23
SAMPLE:CELL POWDER FILE *: 1030 TEMPERATURE =900 C
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SAMPLE:CELL POWDER FILE *: 1030 TEMPERATURE =900 C
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DATE: 12-3-82
lB
REACTION TIME,
M/Z 60 I --1
M/z - 57
M/z - 44
M/z •43
M/z - 32
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M/z - 26
M/z - 16
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15 28
SEC.
M/z • 162 - -
M/z • 144 --
M/z = 126 - -
M/z = 98
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M/z - 70
15 28
SEC.
Figure 17 . Time Dependence of Evolution of Species Responsible for Selected Ions When Filter Paper is Pyrolyzed in 900°C Steam/Argon
24
"' 0 "' "' 0 0
parent ion (e . g . , l evoglucosan); or that the rate limi ting step is
the unzipping of the cellulos e polymer ( e . g . , to l evoglucosan) and
subs equent decomposition ( thermal fragmentation) is very fas t .
Future s tudi es by Evans ( 8) will address thes e ques tions in detail ,
ext ending the time -dependence s tudies to lower temperatures and
fas t er heating rates .
Levoglucosan Pyrolysis Spectra
Early spec tra of l evoglucosanC 1l) showed great s imilarity to the
cellulose spectra. We have begun an elucidation of this s imilarity
by carrying out s tudies with a conventional direct ins ertion probe
( D IP) a Hewl et t -Packard analytical mass spectrometer sys t em, using
both el ectron impact and chemical ionizat ion . Figures 18 and 19
compare spectra of l evoglucosan under different ionization and
instrumental conditions . Als o included is a field ionizat ion
spectrum on the s ame sampl e , kindly suppl ied by Schult en (ZO) .
Comparison of the spectra in Fig . 18 shows that l evoglucosan
undergoes a good deal of fragmentation in the volatil ization and
ioniz ation process . There are two pos s ibl e expl anat ions for this :
( 1) l evoglucosan is thermal ly labil e and is at l east partially
fragment ed by the vol i t il ization process , or ( 2 ) l evoglucosan is
being fragmented by the ionization process itsel f . Th e resul ts in
Fig . 18 coul d be int erpre t ed along either line of reasoning . The
electron impact DIP spectra shows increased fragmentation when the
ion source temperature is raised from 64°C to 200 °C , indicating some
poss ibl e thermal fragmentation . But both show much more
fragmentat ion than chemical ionization using methane indicating that
the ionization process is respons ibl e for fragmentatio n . In
contras t , the free -jet mol ecular -beam EI spectrum res embl es the
CI -CH4 spectra more than the other EI spectra from the D IP. A plausibl e explanation for all thes e observat ions is that the free -jet
adiabatic cooling presents mol ecul es to the ion source with l ow
l evel s of int ernal energy so that the el ectron beam ioniz es a cool
molecul e giving a small er degree of fragmentation. In the D IP, the
mol ecul es are thermally exci ted resul ting in higher l evels of frag -
25
1aa r
90 f aa � 70 f 60 f 50�
40 f 30 f 20 [ 10
. I 100
90
80 w u z 70 a: � 60 f Ill I a: 50� w ' 2: 40 f :I: I _j
30 t w . "'
20 f 10 f I 0j
'"" r 90
80 w u z ,. a: 0 z 60 ::J Ill a: 50 w ;:; 40 >-5 30 w "'
20
10
LEIJOGLUCOSAN
85
127
I I I I 57 I " ' "I ���1
3
J I. LEVOGLUCOSAN
I 60 73
I I It II 98
115 rl
LEVOGLUCOSRN
5� " I
98
LEVOGLUCOSRN
•••
90 60 98
80 w 73 u z 70 a: 0 z 60 ::J Ill a: 50 w ;::: 42 >-5 30 w "' liS
20 IT I 10
50 . ..
"' 0 "' I "' 0
1!45 (d) 0
I I
I I I I I I !63
I I 180 325
( c )
144
I '
(b)
144
!44 (a)
162
I 306 324
180 tSB 234 I I 342 360 l I I ' ' I I !50 200 250 300 350
MASS AXIS, M/Z
Figure 18 . Comparison of Levoglucosan Mass Spectra . (a) Powder vapori z ed in 900°C fl ame . 16 . 5 eV electron impac t. (b) Direct insertion probe at 1 6 5 °C. Ion source at 64 °C . 16. 5 eV. ( c ) Direct ins ertion probe at 16 5°C. Ion source at 200°C . 1 5 . 0 eV. (d) Direc t insert ion probe at 1 6 5 °C. Ionsource at 1 60°C. Chemical Ionization by CH4 .
26
LEVOGLUCOSRN .... 0 "' "'
100 I I ( d ) 8 90 f 1180
I I 90:
,. ( 60 f 50'
w 2: 40 � f--
5 30 � w "' ,. r
10 f LEVOGLUCOSRN
100 1 163 ( c )
••
•• w u z 70 a: Cl z sa ::J "' a: 50 � I w I �
40t I 5
3af
j w "'
20 f 144 1 a � 33 l ,j I
57 Bl 99 I IS •I ' ! I
LEVOGLUCOSRN
100 (b ) •• 144
•• w u z ,. a: Cl z sa ::J 163 "' a: 50 w ;:: 40 f-a: ..J 30 w "'
20
10 133
LEVOGLUCOSRN
100 ( a ) 90 50 144 '" ••
w 73 u z 70 a: Cl z 60 ::J "' a: 50 w ;:; 40 f-5 30
162 w "' 115
I 306 20
IT I 3<4
10 I 180 !98 234 1· 3;' 3i" I I I 50 100 150 200 250 , .. 350
MRSS AXIS, M/Z
Figure 19 . Comparison of Levoglucosan Mass Spectra. (a) Powder vaporiz ed in 900°C fl ame. 16 . 5 eV el ectron impac t. (b) Fiel d desorption. Source temp erature 100 °C. (c ) Fiel d desorption. Source t emperature 50°C. (d) Direct ins ertion probe at 1 5 6°C. Ion s ource at 1 60°C. Chemical ionization by NH3•
27
mentation of the hot mol ecul e in the ionizing el ectron beam.
Increasing th e ion source t emperature from 6 4°C to 200°C increas es
the amount of fragmentation due to the combination of higher thermal
energy and the elec tron beam and not to pyrolysis that occurs during
volatilization . The CI spectra , al though with a 160°C ion source ,
has l es s fragmentation than EI b ecause it is an inherently l es s
energetic ionization process .
In Fig . 19 , the spectra from CI of ammonia is shown to give only
the mol ecular ion ( 180+ = 1 6 2+ + 1 8+) . The addition of NH! ( 1 8 +) is
the least energetic of the CI processes . The lack of fragmentation
is strong evidence that l evoglucosan fragmentation is due to the
ionization process and not to pyrolysis , at leas t at the s e low
t emperatures .
The resul ts from Schul t en's field desorption work is not in
agreement with the above explanation, since increased fragmentation
occurs by increasing the ion source from 50° to 100 °C . Field
desorption is the l east energetic ionization t echnique and such a
large fragmentation patt ern shoul d not be observed by merely
increasing the ion source t emperature 5 0°C . The observed resul t s may
be due to catalytic effects of the emitter , since in thermal
desorption the s ample must be coated on the emit t er and some
catalytic activity may be possibl e .
resolve these'ques tions .
Future work is planned to
Thes e resul ts indicate that by using the free-jet mol ecular-beam
sampling sys t em, l evoglucosan can be detec t ed quantitatively sinc e a
parent ion with 20% relative intensity is produced . However , other
potential pyrolysis products such as l evoglucos enone ( 1 2 6) , 3 -deoxy -
1 , 6-anhydroglucopyranose (144) , and species at masses 98 , 85 , 73, and
60 will be masked by l evoglucosan ionization fragments and ther efore
will be more difficul t to quantitate. A more quantitative comparison
of cellulos e and l evoglucosan spectra, for the low mass range, is
shown in the next s ection .
28
Figure 20.
124 180 I 180
l /; 110 r li I I 't: i1
: i· . "
40 9� ' ,1' ': ;,
I 'i I i! 1381: II ' � �:: ;:1 jl 210"
I I! l 4 I• , , I l ��184 J�· •· 'I ! ! I'
11 ; 'I �: 1 -- -
�-- ---·-- - -
Wheat Straw (Colorado)
Mass Spectra (Low Voltage of llleat Straw and Peat Saaplea in 900•c Argon/Steam. High mass es emphas ized . P eats Ill and 112 appear
· to be high moor and low mo or ,
respectively .
29
t -t· �·
Spectra of Miscellaneous Mat erials- -Fingerprinting
Recent reports<1'2'3'11) have included qualitative spec tra for a
range of carbonaceous material s . Shown here are s everal exampl es to
illus trat e the analytical utility of the high -mass fingerprinting
type of experiment . In Fig . 20 is shown the spec t rum of two peat
sampl es , kindly supplied by Asplund<22) and the spectrum of a
Colorado wheat straw .
In Fig . 21 is shown a spectrum o f polyethyl ene pyrolyzed in hot
flame gas es . Not eworthy are the extremely high mol ecular weight
f ragments preserved without derivatization . Characteris tic
signatures are obtained for other plas tics as well ( 3) . S uch
fingerprinting may be useful in the qualitative charact erization of
wood -derived oil s . Spectra (high mas s tuning condi,tions) are shown
for three oil s , derived from different gasifiers , in Fig . 2 2 . Thes e
I. POLYETHYLENE i 96
I
Figure 21. Spectra of Polyethylene Pyrolyzed in 900°C Steam/ Argon. 17 eV el ectron energy .
Figure 22 . High Mass Spectra of Three Pyrolyis Oils ( exac t origin not well def ined--shown for illus tration of "f ingerprint ing" possibil ities onl y .
3 1
spectra are meant to be suggestive only . We are · in the process of improving the tuning conditions of the mass spectrometer, in the high mass range, in order to make a more careful and controlled comparison of oils (and the feedstocks from which they were derived) that are being provided to us by a number of researchers in North America .
We have now established a standard, reproducible set of ioniza tion and mass spectrometer tuning conditions for the mass range 12 to 200 amu. Under these conditions we are using mixtures of gases and liquids to determine quantitative mass spectral response of pure compounds suspected of being in the primary and secondary pyrolysis slates from woods . In Figs . 23 to 28 are shown a representative set of such spectra, with resolution such that mass assignments are unam biguous .
SECONDARY CRACKING - -PRELIMINARY RESULTS
The sheathed flame gases apparatus shown in Fig . 3 has been tested with cellulose , lignin, and wood . The system works well mech anically and appears suitable for quantitative work. Both singl e and triple specimens give good spectra and signal -to -noise can undoubt edly be improved. A hot -wire spark igniter has been added jus t above the burner surface and small leaks sealed to insure no air enters the column of gases (this has been verified by mass spectra obtained with no specimen in place) .
Figures 29 -31 show the trends in secondary cracking as the pri mary products travel from 5 mm to 160 mm in the approximately 900°C gases before being sampled and rapidly quenched . In comparing the changes in the spectra with distanc e, most significant are the changes in type and relative proportions of ions within one spec trum. A rather large diffusion correction will probably have to be applied to plot quantitative changes in any one ion with distance .
Figure 29 shows the behavior of cellulose at an ionizing elec tron energy of about 20 eV . From 5 to 10 mm above the surface , the spectrum is only slightly altered and the familiar cellulose spectrum is present . Between 10 and 20 mm, major cracking has occurred , mass 78+ (benzene) is becoming prominent and some intermediate ol efins are
Figure 23. Mass Spectra of Conditions Chosen Masses .
------'-- -- -�-- �-
Several Materials for Quantitative
3 3
Under the Standard Calibration at Low
Punky Wood
138 150 164
I j 1 l ··
· · · 1
24
1 I I ,1'1 1 1
UO
L13�1t
· 1 :1 94 . 15o
� i � ·� lotec:h Asoen �
· ·bit· · · ·
1.68 f"' '"' t
0 ;g N 0 0
Figure 24. Mass Spectra of Several Materials Under the Standard Conditions Chosen for Quantitative Calibration at Low Masses. The punky wood derives from pine and is mainly lignin . Note the virtual abs ence of dimethoxy phenol peaks at 154 and 168 in the soft woods .
Figure 25 . Mass Spectra of Several Materials Under the Standard Conditions Chosen for Quantitative Calibration at Low Masses. Note the lack of significant difference in the spectrum of kiln-dried pine heartwood and sapwood .
35
I - -+- � -
42 /
--- - - - - - - -
- -- � . ------ -
�--- -- --�--- --
OI Shale
54
I I l I ··�
-- Texu tJcp11e-
--- - --
. - - � - -- --- ·· ·-
J� ri.JUJ'"'III.MII· .. ·nt..lomll'�
149
I I
1 10
I 124
I l [
• ij 138 94 108 , : I \ I I 66 l I :: I :: I · 150
64 1 70 78 � , \ , ! l 1��� Figure 26 . Mass Spectra of Several Materials Under the Standard
Conditions Chosen for Quantitative Calibration at Low Masses.
36
aL EC:OfUaL
�-------- ----- --�-- ------------ ----------
198 I
Figure 27. Mass Spectra of Several Materials Under the Standard Conditions Chosen for Quantitative Calibration at Low Masses . Note the greater richness of the Ecofuel (solid waste derivative) sample vis-a-vis cellulose .
Figure 28 . Mass Spectra of Several Materials Under the Standard Conditions Chosen for Quantitative Calibration at Low Masses . The gasoline spectrum may be deficient in lighter fractions due to premature flash-off in the presently used flame gas environment .
3 8
z = 77 mm � <0 8
z = 37 mm
z = 20 mm
z = 15 mm
z = 10 mm
z = 5 mm
Figure 29. Secondary Cracking of Primary Pyrolysis Products from Cellulose.
39
probably present . At 40 mm only a (ethylene, CO) , 44+ (C02 , propane) ,
few peaks predominate : 28+
66+ (probably cyclopentadiene f rom thermal decomposition of toluene or phenol since these pure compounds give little 6 6+ at low ionizing electron energies ) , 92+
(toluene ) and 128+ [ possibly naphthalene , which has been detected in the fast pyrolysis of wood ( Z3) ] .
Figure 30 shows similar data for ethanol -extracted , steam exploded lignin. The primary products seem more refractory and com plex changes are shifting the product slate toward lower molecular
+ weight species . Benzene is a major product ion. The prominent 66 peak is higher than can be attributed to the toluene (92+) or phenol (94+) . ( The reader is cautioned not to correlate ion intensities
•
automatically with relative abundances . At these low ionizing electron energies , species with low appearance potentials can easily be over represented in the positive ion mass spectrum . )
Finally , in Fig . 3 1 , the cracking of pine wood is shown. Some new peaks appear to be present , perhaps due to the hemicellulose or extractives components, but the general behavior is consistent with the cellulose and lignin behavior . It appears that 900 ° C and 10 -100 ms time scales are matched to achieve major cracking of pri mary products from wood and its major components .
Because of its relevance in sorting out complex spectra like those just shown , some data for the cracking of methane and propyl ene in the 900°C flame gases are shown in Figs . 32 and 33 . Making a first order correction for diffusion, and recognizing that the sensi tivity for detection of CH4 is only about 1/20th that for ethylene under the conditions of the experiment (low ionizing electron energy) , the methane is seen to undergo only very slight decomposi tion in the approximately 50 ms at 900 ° C . The products seen are most likely acetylene, ethylene, ethane, and co2 , but only in fractional percentages . The propylene shows considerably more cracking under the same conditions ( curves for n -butane, ethane, and methanol were shown previously <24 • 25 ) with the likely production of ethylene , acetylene, propyne ( 39+) and methane) .
Figure 32 . Cracking of CH4 Injected Just Above the Reaction Zone of a H2-o2-Ar Flame
43
;,.. .w .I I'll � .w �
Q) � .w � � !:il
1 5 0 0 42+ + 41+
"i1 26+
0 2s+
• 39+
• 16+
100
50
0 0 1 0 20 30 40 50
Distance. mm
Figure 33 . Cracking of Propylene Injected Just Above the Reaction Zone of a2-o2-Ar Flame
44
.,.
� 0 0
Quantitative Cal ibration for Product Species
Initial attempts have been made to determine relative calibra tion factors for the important pyrolysis products detected by the mass spectrometer . This task is complicated by the use of low elec tron energy, which is necessary to l imit fragmentation. However , this makes reproducible conditions essential since a small charge in ele�tron energy at 18 eV can make a large difference in the relative intensities of different species .
Calibration factors for several gases relative to co2 were determined by bleeding binary mixtures through the central tube of the burner chamber . Relative responses varied with flow rates and with distance from the burner to the sampling orifice, but the importance of these factors is still not certain. Tentative relative response facto.rs for several gases relative to co2 have been calculated : co2=l .OO , CH4=0 . 06� . 0 1 , CzHz=2 . 91� .38 , C0=0 . 26� .0S , CzH4=2 . 59� . 23 , c2H6=0 . 58� . 2 3 , c3H6=14 . 4 1+3 .3 2 , c4H8=10 . 1 5�1 .44 . Confidence inter -vals were calculated at the 90% level . Excessive fragmentation was noted for some of these gases even at the low electron energy setting used , which causes some ambiguity in quantitation.
An initial attempt is currently being made to calibrate response factors for the liquid and solid pyrolysis products also . Compari sons are being made to 5 -methyl furfural (MW=ll O) because it gives a spectrum of high molecular ion intensity with negligible fragmenta tion and thus can be compared to other species without any complica tion due to ambiguous peaks . Ten mg each of 5 -methyl furfural and the substance to be calibrated are placed in a quartz boat and are volatilized on the 900° C steam/ argon environment . Future work will also be done at lower temperatures to minimize pyrolysi s . The molecular ion for each compound is then alternatel:y monitored over the course of volatil ization and the total area under the two curves compared to calculate the relative response of the subs tance of interest . This system allows substances of different volatility to be compared such as methanol and levoglucosan . It also should allow a combined estimate of the effec ts of the diverse factors that con -
45
tribute to the relative intensity of a given peak , such as appearance potential , mass spectometer tuning, and high mass enhancement during the free jet sampling process .
PLANS FOR FY 1983
The directions of the two coordinated tasks in FY 1983 are briefly summarized in this section.
Director ' s Discretionary Task (R . Evans , T . Milne)
The major goals of this task are the identification of the pri mary products of cellulose pyrolysis with emphasis on quantitative yields as a function of time and temperature and on the mechanism of formation. There are several initial questions which need to be answered before meaningful quantitative results can be obtained . The contribution of fragment ions ( from the ionizat"ion process ) to the spectra of pyrolysis products must be determined as has already been described in the case of levoglucosan. This work will be extended to other important products . Another initial ques tion that is being addressed is the establishment of a tuning procedure which balances the needs for resolution and non -discrimination over the mass range of interes t . The establishment o f calibration factors for the pyrol ysis products must be accomplished to correct for mass discrimination in the molecular -beam sampling process and to correct for variation in ionization cross sections for pyrolysis products at the low ion ization voltages used in this s tudy .
An important part of this investigation is the determination of the kinetics of primary product generation as a function of tempera ture . This will be accomplished by looking for variations in the relative abundances of primary products with changes in tempera ture . The existence of competing mechanisms at higher temperatures may increase the usefulness of thermochemical treatments by estab lishing the time and temperature of optimum production of desired products . The heated grid will be used in this investigation. Also planned is the use of tandem quadrupoles (MS /MS ) for positive identi -fication of the primary pyrolysis products . An important part of this effort will be cataloging the spectra of model compounds and
46
possible pyrolysis products under the sampling and ionization condi tions used in these experiments . The final effort in this project will be the construction of an overall mechanism of cellulose primary pyrolysis based on this quantitative and qualitative wo rk .
Biomass Energy Technology Division Task (M. Soltys , T . Milne)
The major emphasis of our work now is the quantitative measure ment of the rates of secondary cracking of the primary products (also quantified) from cellulose , lignin , extractives , and whole wood , with the initial emphasis on cellulos e. Such measurements will involve :
a) Measurement of corrected temperatures throughout the gas column, with and without, the presence of pyrolyzing substances and with and without the perturbation of extractive sampling .
b) Careful measurement of relative response of the sampling system/mass spectrometer under both low and high ionizing electron energy, and under reproducible mass spectrometer tuning conditions , for high and low masses . This will involve metered gases and liquids under temperature and dispersion conditions s imulating those of the actual pyrolysis .
c ) Measurement of statistically reproducible mass spectra of pyrolyzing primary products as a function of temperature and time in hot columns of steam-inert gas and inert gas alone .
d) Measurement of cracking of pure compounds identical to, or representative of , primary pyrolysis products (e . g . , levoglucosan, acetic acid, phenol ) .
Such data should have immediate applied usefulness not only in optimizing conditions for production of valuable products such as ethylene and aromatics but in assessing the conditions needed to destroy refractory organic tars and oils (an extension of such s tud ies to oxidative environments would have great relevance to the use of injected o2 to clean up gasifier effluent streams or combustion generated creosotes ) .
47
ACKNOWLEDGEMENTS
The authors woul d l ike to acknowl edge helpful discus s ions with
Henk Meuzelaar ( U . of Utah) and collaborat ive experiments and discus
s i ons with Hans -Rol f Schul t en (Fachhockschul e Fres enius ,
Wi esbaden) . Gunther Holzer ( Colorado School of Mines) provided much
assistance in the direct ins ertion probe -CI work on the HP mass spec
trometer. Continued consultation regarding the heated -grid apparatus
with Will iam Peters (MIT) is al so appreciated . Dianna Barney is to
be thanked for producing the comput er -generated and other graphics .
Thanks also to Hel ena Chum and her group for providing the steam
expl oded aspen l igni n . Don Stevens (PNL) has been mos t helpful as
t echnical monitor . Part ial support from the SERI Director ' s Devel -
opment Fund is also grateful ly acknowl edged .
48
REFERENCES
1 . Milne , T . A . , and M. N . Sol tys , 198 2 , Fundamental Pyrolysis
Studi e s : Qua r t erly Repor t , October -Dec embe r, 198 1 . SERI/PR -234 -
1 5 37 . Solar Energy Res earch Ins titut e : Golden, CO .
2 . Milne , T . A. , and M. N . Soltys , 1 98 2 , Fundamental Pyrolysis
Studi e s : Quarterly Repor t , January -March, 198 2 . SERI/PR -234 -
1 6 1 7 . Solar Energy Res earch Ins t itut e : Gol den, C O .
3 . Milne , T .
Studies .
A. , and M . N . Sol tys , 1982 , Fundamental Pyrolysis
SERI/TP -23 4 -1 66 5 . Solar Energy Research Ins titut e :
Golden, co .
4 . Milne , T . A. and M. N . Sol tys , "Direct Mass -Spectrometric Studies
of the Pyrolys is of Carbonaceous Fuel s . I. A Fl ame -Pyrolysis ,
Mol ecul ar -Beam Sampl ing Technique . " Accept ed for publ ication in
Journal of Analytical and Appl ied Pyrolys i s .
5 . Milne, T . A . and M . N . Solty s , "Direct Mass -Spectrometric S tudies
of the Pyrolysis of Carbonaceous Fuels . II . Qual itative
Obs ervations of Primary and Secondary Proces s es in Biomas s . "
Accep t ed for publ icat ion in Journal of Analytical and Appl ied
Pyrolys i s .
6 . Fundamental s of Thermochemical Biomass Convers ion : An
International Conf erenc e . Est es Park , CO; 18 -2 2 Oc t . 1982 .
7 . Milne , T . A. Spectrometric
Behavior of
and M . N. Soltys , 1982 , "The Direc t , Mass
Study of the Pr imary and Secondary Pyrolysis
Biomass and Its Cons tituents . " International
Conference on Fundamentals of Thermochemical Biomas s Conversion ;
Estes Park , C O; 18 -22 Oc t . 1982 .
49
8 . Evans , Robert J . "Mechanis tic Studi es of the Pyrolys is of
Biomass -Rel ated Oxygenated and Aromatic Compounds . " SERI
Director ' s Discret ionary Fund Project No . 2704 ( 1 982 -83 ) .
9 . Hajal igol , M. R . , w. A. Peters , J . B . Howar d, J . P . Longwel l ,
1981 , "Product Composit ions and Kinetics for Rapid Pyrolysis of
Cellulos e . " Proceedings of the Spec ial ists Workshop on the Fas t
Pyrolysis of Biomass ; Copper Mountain, CO; 19 -22 Oct . 1980 .
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10 . Broido , A. and F . J . Kilzer, 196 3 , Fire Res earch Abs trac ts and
Revi ews . Vol . S ; p . 1 S 7 .
1 1 . Milne , T . A. and M . N . Sol tys , 1 9 8 1 , Fundamental Pyrolysis
Studi e s : Annual Report for Fiscal Year 198 1 . SERI/PR -23 4 -14S 4 .
Solar Energy Res earch Ins t itut e : Golden, C O .
1 2 . Ohnishi , A. , E . Takagi , and K . Kato , 1976 , "Curie -Point
Pyrolys i s , Gas -Liquid Chromatography of Xylan. " Carbohydrat e
Res earch . Vol . SO ; p . 2 7 S .
13 . Meuzelaar , H . L . c . , P . G . Kis temaker , and M . A. Pos thumus , 1974 ,
Biomed . Mass Spect rum. Vol . 1 ; p . 3 1 2 .
1 4 . Schul ten, H . -R . and w. Gort z , 1978 , "Curie -Point Pyrolysis and
Fiel d Ionization Mass Spectrometry of Polysaccharides . " Anal .
Chem . Vol . SO ( No . 3) : p . 428 .
1 S . Hil eman , F . D . , L . H . Wo jc ik , J . H . Futrell , and F . N . Einhorn ,
197 6 , "Comparison of the Thermal Degradation Produc ts of a
Cellulose and Dougl as Fir Under Inert and Oxidative
Environment s . " Thermal Uses and Properties of Carbohydrat es and
Lignins . Edit ed by F . Shaf izadeh , K. Sarkanen , and D . Tillman .
Academic Press ; p . 49 : New York .
50
1 6 . Frankl in , w. E . , 1979 , Analyt . Chern . Vol . 51 ; p . 992 .
17 . Lincoln, K. A. , 198 1 , "High Radiat ive Heat Flux Pyrolys i s of Thin Biomas s . " Proceedings of the Special is ts i-brkshop on the Fas t Pyrolysis of Biomass ; Copp er Mountain, CO; 19 -22 Oct . 1 9 8 0 . SERI/CP -62 2 -109 6 . Solar Energy Research Ins titut e : Gol den, CO;
pp . 1 5 3 -63 .
18 . Haider , K. , B . R . Nagar, c . Saiz , H . L . c . Meuz elaar , and J . P .
Martin, 1 97 7 , " S tudies on Soil Humic Compounds , Fungal Melanins
and Model Polymers by Pyrolysis Mass -Spectrome try . " Soil Organic
Mat ter Studi es . Vol . I I; pp . 2 1 3 - 19 . Intl . At omic Energy
Agency , Vienna.
1 9 . Meuz elaar , H . L. C . , J . Haverkamp , and F. D. Hil eman , 1982 ,
Pyrolysis Mass Spectrometry of Recent and Foss il Biomat erial s .
El s evier Scientific Publ ishing Company : Amster dam .
20 . Schul t en , H . -R .
communication.
(Universi tat Bonn , G . F . R . ) , 1982 , Private
2 1 . Chum, H. ( Solar Energy Res earch Ins titut e , Golden, CO) , 1982 ,
Private communication.
22 . Asplund , D . , 1982 , Suppl ied Finnish peats of two types .
23 . Diebol d , J . ( Solar Energy Research Ins titut e , Gol den, CO) , 1982 ,
Private communication .
2 4 . Milne , T . A. and M . N . Soltys , 1 98 1 , Kinet ics and Mechanisms of
Fas t Pyrolys i s : Quarterly Report - January -March 198 1 . SERI/PR -
6 2 2 -1 1 5 2 . Solar Energy Res earch Ins titut e : Golden, CO .
25 . Milne , T . A. and M . N . Soltys , 198 1 , Pyrolysis Mechani sms :
Quart erly Report - April -Jun e, 19 8 1 . SERI/PR -6 2 2 -134 7 . Solar
