Synthesis and Assessment of Process Systems for Production of Ammonia using Nitric Oxide

in Combustion Exhaust Gas

Hideyuki Matsumoto1, Shotaro Ogawa1, Keisuke Kobayashi2,Tetsuya Nanba2, Shiro Yoshikawa1, Taku Tsujimura2, HirohideFurutani2

1) Department of Chemical Science and Engineering, Tokyo Institute of Technology2) Renewable Energy Research Center, National Institute of Advanced Industrial Science and Technology (AIST)

2019 AIChE Annual MeetingNH3 Energy+ (November 14, 2019)

Production of Ammonia using nitric oxide in combustion exhaust gasn Industrial Ammonia Production

n NOx ⇒ NH3 (NTA)

Haber-Bosch method(200-500 atm, 400−600℃)

FertilizerChemicalsNH3-SCRFuelH2

N2Air

CH4

H2O

Activation and dissociation ofN N (945 kJ)

NOxN2 + O2

Combustion

HC, CH4

New NTA method(Ambient pressure,100−400℃)

FertilizerChemicalsNH3-SCRFuel

Activation and dissociation ofN O (632 kJ)

Approx. 250 million ton of NH3 could be produced by using a half of NOx (4%) in exhaust gas from all the thermal power plants located in Japan. ⇒ Reutilization of produced NH3 as fuel will bring about decrease in CO2 emissions.

From the perspective of “Nitrogen Cycle”Conceptual model of where interventions in the nitrogen cycle can be used to decrease the amount of reactive nitrogen (Nr) created or the amount of Nr lost to the environment.

J. N. Galloway et al.: Science, 320, 889-892 (2008)

Agenda

n Background for development of process systems for NH3 production using NO in combustion exhaust gas (NTA system)

n Development of new catalytic process for conversion of NO to NH3(NTA) : NO-CO-H2O reaction process

n Simulation analysis for effects of application of the proposed NTA system combined with lean-rich cycling operation for combustor(e.g. reciprocating engine generator)

n Conclusions

2NO + 5H2 → 2NH3 + 2H2O

4NO + 4NH3 + O2 → 4N2 + 6H2O

■ Ammonia formation during catalytic NOx reduction[1]

[1] J.R. Theis et al.; SAE Tech. Pap. (2011)

NOx, CO2SOx

It has been reported that complete selectivity for NH3 is difficult to achieve by means of the NO–H2 reaction under stoichiometric conditions.

■ Development of catalytic process for conversion of NO to NH3 (NTA) [2, 3]

NO + 2.5CO + 1.5H2O → NH3 + 2.5CO2Pt/TiO2

High NO conversion and NH3 selectivity at ambientpressure and temperatures below 300 °C

[2] T. Nanba et al.; Chem. Lett., 37, 710-711 (2008)[3] K. Kobayashi et al.; Catal. Sci. Technol., 9, 2898-2905 (2019)

Reaction route for conversion of reactive nitrogen to ammonia

Effect of the crystal type of TiO2 on catalytic activity

It was shown that Pt/TiO2 was higher activity than M/TiO2 (M: Rh, Ir, Ru, Pd).

●: Pt/TiO2(A)1■ : Pt/TiO2 (A)2◆: Pt/TiO2(R) ▲ : Pt/TiO2 (AR)80※A: anatase, R: rutile

AnataseFeed gas1000 ppm NO, 3000 ppm CO, and 1% H2O

l It was observed by DRIFT (the diffuse reflectance infrared spectroscopy) that CO exhibited strong interaction with platinum on the rutile TiO2.

l it was estimated that the strong interaction of CO with Pt reduced the reaction activity by comparing with Pt/anatase-TiO2 catalyst.

Conceptual design of process systems for production of NH3 using NO in combustion exhaust gas

Generation of alternatives

Investigation,Data collection

Simulation Evaluation

Type of combustor and its scale

Unified NTA reaction system

Tool

NONO NH3NH3

Reducing agent

Reducing agent

l Energy savingl CO2 emissions

Two-stage NTA reaction system

(i) Adsorption & desorption of NO

(ii) Conversion of NO to NH3Effect of existence of O2

Effect of temperature and flow rate of feed gas ⇒ physical or chemical ?

Adaptation of lean-rich cycling operation for combustor

NO + 2.5CO + 1.5H2O → NH3 + 2.5CO2

Combustion

Hydrocarbon fuel

Air

ReductionReducing agent NO adsorption

NTA reaction

NH3

Combustion

HC fuel

Air

NO adsorption

NTA reaction

NH3Exce

ss a

ir ra

tio

Time

Lean burning

Rich burning

For case of reciprocating engine generator

Simulation analysis for effects of application of NTA system

n Simulation for composition of exhaust gas of combustion engine

l

t

Rich burning

Excess air ratio (l) [-]1.4 – 4.9%

CO

, CO

2, O

2, H

2, H

2O [v

ol%

]

NO

[x103ppm

]

Zero-dimensional simulation model

l The extended Zel’dovich mechanism for NO formationl Six equilibrium reactions for combustion

N2+O⇄NO+NN+O2⇄NO+ON+OH⇄NO+H

Fuel (Model): Decane (T = 300 K, P = 1.5 atm)

n Search of optimum ratio of cycle time (rich-burn/lean-burn)

Excess air ratio (l) in rich-burn = 0.797,0.661,0.526

Component ratio in feed to the NTA reactor was the stoichiometric ratio for NO and (CO + H2), i.e. 2 : 5.

n Simulation of NTA process

Gibbs reactor model (Aspen HYSYS V9)Equilibrium reaction model

Operating conditions

NO concentration in lean-burn = 500 – 2000 ppm

Influence of lean-rich cycling operation to reduction in CO2emissions in NTA system

113

113.5

114

114.5

115

115.5

116

116.5

0.5 0.6 0.7 0.8

CO

2[m

ol/m

in]

λ [-]

R1&R2R1

2.26

2.28

2.3

2.32

2.34

2.36

2.38

2.4

0.5 0.6 0.7 0.8

NH

3[m

ol/m

in]

λ [-]

R1&R2R1

R1: 2NO + 5CO + 3H2O → 2NH3 + 5CO2 R2: 2NO + 5H2 → 2NH3 + 2H2O

T = 250 ℃CNO =2000 ppm

※Evaluation index: Ratio of CO2 emissions [mol] to the total heat of combustion for the consumed decane and the produced ammonia [kJ]

Reduction in CO2 emmisions on the basis of the NH3 SCR system ⇒ approx. 1%

Influence of lean-rich cycling operation to reduction in CO2 emissions in NTA system

Influence of NO conc. under lean-bun operation Influence of excess air ratio under lean-bun operation

Reduction rate for CO2 emissions (%)＝𝐴0 − 𝐴 ∗ 100

𝐴0

A＝Amount of CO2 emissions [mol]

Heat of combushon for the consumed decane [kJ]+Heat of the produced NH3 [kJ]

※A0: NH3 SCR system

Simulation of reactor performance of the developed catalyst (Pt/TiO2 (A))

-2.8

-2.6

-2.4

-2.2

-2

-1.8

-1.6

0.00185 0.00195 0.00205 0.00215

ln r

[-]

1/T [1/K]

n Kinetic analysis of NO-CO-H2O reaction using Pt/TiO2 (A)

-2.3

-2.2

-2.1

-2

-1.9

-1.8

-1.7

-1.6

4.5 5.5 6.5 7.5

ln r

[-]

ln PNO(Pa) [-]

-2.2

-2.1

-2

-1.9

-1.8

-1.7

-1.6

6 6.5 7 7.5 8

ln r

[-]

ln PCO(Pa) [-]

E = 35.1 kJ/mol

[Experimental conditions] T:200〜250 °C , CNO:1000-8000 ppm, CCO:5000-20000 ppm, CH2O:6000-18000 ppm, Total flow rate: 250ml/min, Catalyst : 0.25g

Influence of reaction temperature to behavior of NTA system

R1: 2NO +5CO + 3H2O ⇒2NH3 + 5CO2R2: NO+(5/2)H2 ⇒ NH3 + H2OR3: 3NO + 2 NH3 ⇒ (5/2)N2 + 3H2OR4: 2NO + H2 ⇒ N2O + H2OR5: 2H2 + 2NO ⇒ 2H2O + N2R6: 2CO + 2NO ⇒ 2CO2 + N2R7: CO + H2O ⇒ CO2 + H2

Reaction A(1/s) Ea(KJ/mol)

R1 1.76x107 35.1R2 2.61x1016 128R3 1.25x1012 91.1R4 2.28x1010 85.0R5 5.29x107 69.2R6 1.92x106 52.3R7 1.21x102 56.7 M. Li et al.; Applied Catalysis B: Environmental, 242, 469-484 (2019)

𝑟@ = 𝐴@𝑒𝑥𝑝 −𝐸F,@R𝑇

𝑋KL𝑋ML𝑋NOL𝐶QRSR1

R2 𝑟O = 𝐴O𝑒𝑥𝑝 −𝐸F,OR𝑇 𝑋KL𝑋NO𝐶QRS

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

150 200 250 300

T [℃]

NH

3[m

ol/m

in]

CNO =2000 ppm

l = 0.5935tR = 1.08 s

PFR Model(SimCentral 3.3)

Conclusionsn The developed NTA process using Pt/TiO2 has demonstrated to be effective

under low temperature condition (< 250 °C ) by controlling feed of CO, byexperiments and simulations.

n It was expected that positive emission of nitric oxide in combustor couldenhance reduction of CO2 emissions by combing with NTA reaction (NO-CO-H2O reaction).

n Future work is to synthesize the NTA reaction process with a process foradsorption and concertation of nitric oxide, and to asses effects of reduction inCO2 emissions for the unified system.

(i) Adsorption & desorption of NO (ii) Conversion of NO to NH3Effect of existence of O2physical or chemical ?

Type of combustorl Flow ratel Compositionl Temperaturel Pressure