Silylation and MnO modifications of solid acids for

Toluene Methylation to p-Xylene

Presentation By :- Vijaykumar.S.M

December 31-12- 2010

Poornaprajna Institute of scientific research ,Bangalore.

Silylation Process

Silylation is a process in which zeolite (eg:HZSM-5) is treated with silicon compound selected from the group of alkoxysilane and polysiloxanes .

TEOS TMOS POLYSILOXANE

In Silylation the Silicon compound react with the external Surface Silanol group of zeolite and Reducing the Pore size so that only para xylene can pass through the pore.

OH

OH

OH

OH

O O

H

O

H

O

H

O

H

O

H

Si(OEt)4

H

Si OEt

OEt

EtO

OEt

pore Zeolite Surface

Silyalation Process

CH3

CH3

CH3OH

Effect of silylation

Effect of Silylation

CH3OH

CH3

CH3

CH3

Silylation By TEOS Ex-situ

A mixture of TEOS, toluene and methanol is contacted in vapour or liquid phase with zeolite.

Due to large kinetic diameter of TEOS, it reacts only with the –OH groups on the external surface of zeolite.

Decomposition of surface organic moiety by calcination, leaves coating of inactive SiO2 on the external surface of zeolite.

Results in passivation of the active sites on external surface.

TEOS is inexpensive as compared with Polysiloxane.

Lab Procedure for making Extrudates

1M NH4NO3 Reflux for 6 h

Filter & Dry

alumina binder

Mixed well

Activation at 813K

18% aq. AcOH

Lab Procedure for Silylation

Activated Extrudates

TEOS, MeOH,

Toluene

Reflux

6 Hour

Distill out solvents

1 Hour

Cool

add Water

After 30 min

Dry At 393 K

calcination

1 silylated extrudates

Patent No

Catalyst Reaction Condition Toluene Conversion

P-Xylene selectivity

4613717Research ASSo light oil,Tokayo,japan(1985)

AZ-1,AZ-2,Az-3 (1,8 diamino 4 aminomethyloctane)HZSM-5(Al,Cr,B)S.A -Silicic acid ester (vapour)Calcine in presence of oxygen.

Tol/MeoH=2,WHSV=4/Hr,T=450, P=1atmFixed Bed reactor

20%(mole)

95%(Wt%)

7387978B2Chevron phillip chemical companyLP,TX(US)

HZSM-5,Silica Binder(1/16 extrudates.calcinedS.A- 10Wt% Poly(Methyl phenyl)Siloxane.(cyclohex)Steaming ,0.1HCl Treatement,wash with water ,calcined.

Tol/MeOH=4,WHSV=20ml/Hour,H2 =260ml/min,T= 600 c, P=5-6 atm,Time 7.5 Hour 11.5%

(total xylene yield)

100%

HZSM-5 ,S.A-10% TEOS ,Silica Binder, Extrudates ,S.A-Poly(Methyl phenyl)Siloxane.(cyclohexane),calcine .

Tol/MeOH=4,WHSV=20ml/Hour,H2 =260ml/min,T= 600 ,P=5-6 atm,Time 7 Hour

21.5(total xylene yield)

84.6%

Patent No

Catalyst Reaction Condition Toluene Conversion

P-Xylene selectivity

4127616Mobil Oil company1978

H-Zsm-5,S.A-Phenyl Methyl silicone,(n-Hexane)Pelletes(14-30mesh),calcine.7.5 Wt% Silica .

H2/HC=2 ,WHSV=10/HrT=400-550,P=1atm

T=400T=450T=500T=550

36 44 60 84

959491 Wt%88

4283306E I Du Pont de Nemours company,,wiliington(1981)

HZSM-5,

5%TEOS(Pyridine)Tol/MeOH=3,WHSV=3.9 /Hr,H2/HC=0.8P=1atm.

T=450T=500T=550T=600

Mole%13.416.618.820.1

Wt%949393 92

7321072B2Johnson Matthey,PLC,London2010

(Low contact time)10 wt% Mg/ HZSM-5 (SAR = 80)HZSM-5 + 10% aq MgNO3 impregnated, dried, calcined 500 C

. T = 440 , Tol/meOH = 8, Flow rate= 999 ml h-1

H2 = 66.6 ml min-1, water : feed = 1, WHSV of toluene = 33.35 h-1, time = 7h

12.6%Wt%

98.8%Wt%

Patent No Catalyst Reaction Condition Toluene Conv

p-Xylene selecty

10Wt% B/HZSm-5 WHSV=11.12/Hr,Contact time=0.33sec,Tol/MeOH=1.3,T=450c

WHSV=33.35 T/M=8 T/M=4 T/M=1.3

C.T=0.1sC.T=0.115C T=0.11s

32% mol%

12.5%24.1%22.6%

94.6mol%

99%98.3%94.8%

6864200 B2IPCl BARODA2005

Silanated Ga-AlZSM-5 (35 wt% on alumina binder)Preparation: GaAlZSM-5 H form + alumica binder was silanated twice with TEOS by repeated soak and dry method, calcined at 535 °C.

Fixed bed continuous flow reactor. Temp = 450 °C, Toluene : methanol = 2:1 WHSVtoluene = 3.5 h-1

25.8% 85.1%wt%

7494951B2China petroleum corporation Beijing(2006)

ZSM-5 ,S.A*-Dimethylsilicone oil *Benzyl silicone oil &Dimethyl silicon oil*Diamine silicone oil &Dimethyl silicone oil(Solvent n-Hexane)

WHSV=4/Hr,T=440c,P=5atm ,H2/HC=2

Wt%30.8%

30.7%

30.1%

Wt%90.7%

90.4%

90.5%

Patent No

Catalyst Reaction Condition Toluene Conversion

P-Xylene selectivity

Tech overview report on Toluene methylation IPCL, Baroda 2002

Silanated HZSM-5 (SAR 240)65% HZSM-5 with alumina binder, extrudate, added TEOS in toluene+ methanol mixture, solvents distilled out, water added, dried and calcined 540°C

Fixed bed continuous flow reactor. Catalyst wt = 1g, Temp = 425 °C, Toluene : methanol = 4:1 WHSVtoluene = 5.3 h-1

H2 : feed = 2 15.7 wt% 87.1%wt%

Catalyst pilot plant Catalyst wt = 100g, Temp = 430 °C, Toluene : methanol = 8:1 WHSVtoluene = 3.4 h-1

H2 : feed = 2,

After 3 cycles

29.7%wt%

85.9%wt%

US7074739 B2Dekka et alExxon Mobil Chemical patents2006

17 wt% LaxOy/ ZrO2 physical mixture with steamed HZSM-5 (SAR = 450).

Fixed bed continuous flow reactor. Temp = 585 C, Toluene : methanol = 2:1 WHSV = 8 h-1

H2 : feed = 2, water : feed = 2, pressure = 2.8atm

32 %(after 25 h)

28(after140hr)

89 wt%

83wt%

Reaction condition's:T=523K,WHSV=2.5 /Hr, Tol:MeOH=1:1.5 time on stream=6hr, P=1atm, Reactor :continuous Down flow reactor.

Catalyst :Dodeca-Molybdo Phosphoric acid(PMA)loaded on clay with Surface area :176 m2/gram

Toluene Alkylation with Methanol to P-Xylene over Heteropoly Acids Supported by Clay

Journal of natural gas chemistry 16(2007)42-45

Effect of Pt on stability of nano-scale ZSM-5catalyst for toluene alkylation with methanol into p-xylene

Reactor :Continous Flow Fixed Bed reactorReaction condition's :460 c ,WHSV=2 /Hr, Tol/MeOH =2 , H2/HC=8,water/HC=8 .P=1 atm. Catalyst a:

3%SiO2+5% P2O5+3% MgO+3%SiO2+0.3% Pt/nanoscale –ZSM-5

Catalyst b:3%SiO2+5% P2O5+3% MgO+3%SiO2+1.0% Pt/nanoscale –ZSM-5

Catalysis Today(2010)

Toluene Alkylation to selective Formation Of P-Xylene Over Co-Crystalline ZSM-12/ZSM-5

Catalyst : ZSM-12(A),ZSM-5/ZSM-12(B),ZSM-5(C),

Reaction Condition :T=573K ,Tol/MeOH=1:2,LHSV=2.5/Hr, P=1atm.catalyst Wt=4gm.

Reactor: Fixed Bed continuous Flow reactor

Journal of Natural Gas chemistry 16(2007)37-41

The Roles and Structure Of Zeolite for catalyzing Toluene Alkylation With Methanol to xylene

Microporous and Mesoporous marterial88(2006)16-21

Zeolites with higher number of mid strength acid sites show high catalytic activity Eg: ZSM-5(SAR-136),SAPO-11, MCM-22.

The Acidic site required For Catalyzing toluene alkylation with methanol are lower in strength than those for Catalytic toluene disproporation

Summary* By using different Silylating agent or Mixture of silylating agents can give good yield on toluene methylation.Tetra Ethyl orthosilicate ,Poly siloxane ,Diamine silicone oil Benzyl silicone oil ,dimethyl silicone oil,Tetratertiarybutoxysilane etc.

* By Lowering the contact time to 0.1 Second a good selectivity has been observed

*Use of suitable binder like alumina and Silica Will selectively enhance the p -Xylene selectivity.

* With Impregnation of different metal oxides like LaOx, MgO, ZrO2 on zeolites can give good selectivity.

Other methods by which p-xylene yield can be increased are

* By Loading Superacids like phosphomolybdic acid on suitable support.

• Synthesizing nano zeolite And Impregnating with nobel metal like Pt,Pd etc,which reducec coke formation on zeolite.

* By using Co crystalline Zsm-5/Zsm-12 Zeolites .

•Use of zeolites with 10-membered pore opening and higher number of moderate acidic sites like ZSM-5,MCM-22,SAPO-11.