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Industrial Chemistry

Synthesis of hydrogen cyanide in a solid-electrolyte-cell reactor

Profile image of Nikolas KiratzisNikolas Kiratzis

1993, Industrial & Engineering Chemistry Research

https://doi.org/10.1021/IE00021A014
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Abstract

A kinetic model was prepared for the simulation of the production of HCN in a yttria-stabilizedzirconia cell that uses CH4-NH3 mixtures as fuel. The model considers 14 surface reactions occuring simultaneously at the anode. The effects of temperature, 0% flux, inlet gas composition, and inlet gas velocity on the HCN yield and on the overall exothermicity of the system were examined. It was found that the cell can operate without external heat supply if the CHJNH3 feed ratio is higher than 1.25. Two different cell designs were examined, one in which the anode is inside the zirconia tube, and one in which air flows inside the tube and the fuel flows outside perpendicular to the direction of air flow. The latter design exhibits certain additional advantages over the traditional tubular cell design. Cowans, B. A.; Jurman, K. A.; Delgass, W. N.; Li, Y. Z.; Reifenberger, R.; Koch, T. A. Scanning Tunneling Microscopy of Platinum-Rhodium Gauze HCN Catalysts. J. Catd. 1990,125, 513. Debenedetti, P. G.; Vayenas, C. G.; Yentekakis, I.; Hegedus, L. L. Mathematic Modeling of Cross-Flow, Solid State Electrochemical Reactors. ACS Symp. Ser. 1984,237, 181. Grosz, F.; Zegers, P.; Singhal, S. C.; Yamamoto, 0. Proceedings of the Second International Symposium on Solid Oxide Fuel Cells, Athens; Commission of the European Communities: Luxembourg, 1991. Hasenberg, D.; Schmidt, L. D. HCN Synthesis from CHI and NH3 on Clean Rh. J. Catal. 1985, 91, 116. Hasenberg, D.; Schmidt, L. D. HCN Synthesis from C& and NH3 on Clean Pt. J. CUtUl. 1986,97,166. Hasenberg, D.; Schmidt, L. D. HCN Synthesis from C&, NHa and 0 2 on Clean Pt. J. C4td 1987, 104,441. Kiratzis, N.; The Synthesis of Hydrogen Cyanide ina Solid Electrolyte Fuel Cell. Ph.D. Thesis 1991, Tufta University. Kiratzis, N.; Stoukides, M. The Synthesis of Hydrogen Cyanide in a Solid Electrolyte Fuel Cell. J. Electrochem. SOC. 1987, 134, 1925. Kiratzis, N.; Stoukides, M. Kinetics of the HCN Synthesis in a Solid Electrolyte Cell. J. C4td 1991,132, 257. Kirk-Othmer Encyclopedia of Chemical Technology, 3rd ed.; Grayson, M., Ed.; Wiley: New York, 1978. Koberstein, E. Model Reactor Studies of the Hydrogen Cyanide Synthesis from Methane and Ammonia. Znd. Eng. Chem. Process Des. Deu. 1973,12,444. McKenna, L. A. Modeling of HCN Synthesis in a Solid Electrolyte Fuel Cell. M.S. Thesis 1992, Tufts University.

Figures (14)
Figure 1. Schematic diagram of tubular reactor design (TRD). The Model The Tubular Reactor Design (TRD). Two cell designs have been examined. Figure 1 is a schematic of a tubular reactor cell. Yttria-stabilized zirconia (YSZ), a solid-state O?- conductor, is used as the electrolyte. Methane and ammonia are fed inside the YSZ tube which has inside diameter d,, wall thickness e, and tube length L. A platinum film is deposited on the inside cylindrical surface to serve as anodic electrode. The choice for cathodic electrode does not affect the present simulation results, and therefore it can be any metal or conducting perovskite typically used in solid oxide fuel cells (Grosz et al., 1991). The cathode is exposed to air. The anode (catalyst) surface area is A, and the reactor volume (anode side) is V. Thus the cell can be considered a Degussa reactor in which the ceramic peripheral walls are permeable to oxygen.
Figure 1. Schematic diagram of tubular reactor design (TRD). The Model The Tubular Reactor Design (TRD). Two cell designs have been examined. Figure 1 is a schematic of a tubular reactor cell. Yttria-stabilized zirconia (YSZ), a solid-state O?- conductor, is used as the electrolyte. Methane and ammonia are fed inside the YSZ tube which has inside diameter d,, wall thickness e, and tube length L. A platinum film is deposited on the inside cylindrical surface to serve as anodic electrode. The choice for cathodic electrode does not affect the present simulation results, and therefore it can be any metal or conducting perovskite typically used in solid oxide fuel cells (Grosz et al., 1991). The cathode is exposed to air. The anode (catalyst) surface area is A, and the reactor volume (anode side) is V. Thus the cell can be considered a Degussa reactor in which the ceramic peripheral walls are permeable to oxygen.
Table I. Reactions and Reaction Rates * Rate expressions and kinetic constants (except 13) are taken from Waletzko and Schmidt (1988).
Table I. Reactions and Reaction Rates * Rate expressions and kinetic constants (except 13) are taken from Waletzko and Schmidt (1988).
Figure 3. Model predictions for isothermal operation of the TRD at 1100 K; J = 1.2, de = 1, Pun, = 200, Pou, = 300, A/V = 40, uo = 500. (a,b) Dependence of partial pressures of reactants and products on methane conversion, xcy,. (c) Dependence of Q and Q, on xcu,.
Figure 3. Model predictions for isothermal operation of the TRD at 1100 K; J = 1.2, de = 1, Pun, = 200, Pou, = 300, A/V = 40, uo = 500. (a,b) Dependence of partial pressures of reactants and products on methane conversion, xcy,. (c) Dependence of Q and Q, on xcu,.
Figure 4. Model predictions for adiabatic operation of the TRD at 1100 K; J = 1.2, d, = 1, A/V = 40, wo = 500. (a, b) Dependence of partial pressures of reactants and products on methane conversion, xcu, (c) Dependence of adiabatic temperature on xcH,.
Figure 4. Model predictions for adiabatic operation of the TRD at 1100 K; J = 1.2, d, = 1, A/V = 40, wo = 500. (a, b) Dependence of partial pressures of reactants and products on methane conversion, xcu, (c) Dependence of adiabatic temperature on xcH,.
Figure 5. Effect of J on adiabatic temperature, T, Syon, and L* for adiabatic operation of the TRD. Parameter values are kept as in Figures 3 and 4. (a) Dependence of T on xcy, for various J values. (b) Dependence of L* and Sycn on J. L* is the length at which T = Ty; ie, the reactor temperature becomes equal to the feed temperature. Sycn is the ratio of moles of HCN produced over the moles of NH3 consumed.
Figure 5. Effect of J on adiabatic temperature, T, Syon, and L* for adiabatic operation of the TRD. Parameter values are kept as in Figures 3 and 4. (a) Dependence of T on xcy, for various J values. (b) Dependence of L* and Sycn on J. L* is the length at which T = Ty; ie, the reactor temperature becomes equal to the feed temperature. Sycn is the ratio of moles of HCN produced over the moles of NH3 consumed.
Figure 7. Effect of tube diameter on operation of the TRD; J = 1.2, Pyu, = 200, Pow, = 800, A/V = 40, uo = 500. (a) Isothermal operation at 1100 K; effect on Q. (b) Effect on adiabatic temperature.
Figure 7. Effect of tube diameter on operation of the TRD; J = 1.2, Pyu, = 200, Pow, = 800, A/V = 40, uo = 500. (a) Isothermal operation at 1100 K; effect on Q. (b) Effect on adiabatic temperature.
Figure 9. Model predictions for isothermal operation of the CFD at 1100 K; d, = 1, Pun, = 200, Pou, = 300, A/V = 40, u = 500, h = 0.5. (a) Dependence of Don zenjfbr vaflous Jab. (b) Dependence of L* and Syon on J. Figure 10. Model predictions for isothermal operation of the CFD at 1100 K; J = 1.2,h = 1, Pru, = 200, Pou, = 300, A/V = 40, u = 500. (a) Dependence of Q on xcu, for various M values. (b) Dependence of L* and Sycn on M. and 1.5 serves two purposes well, autothermal operation and high Sycn. Similar to the TRD, the model predictions
Figure 9. Model predictions for isothermal operation of the CFD at 1100 K; d, = 1, Pun, = 200, Pou, = 300, A/V = 40, u = 500, h = 0.5. (a) Dependence of Don zenjfbr vaflous Jab. (b) Dependence of L* and Syon on J. Figure 10. Model predictions for isothermal operation of the CFD at 1100 K; J = 1.2,h = 1, Pru, = 200, Pou, = 300, A/V = 40, u = 500. (a) Dependence of Q on xcu, for various M values. (b) Dependence of L* and Sycn on M. and 1.5 serves two purposes well, autothermal operation and high Sycn. Similar to the TRD, the model predictions
for adiabatic operation do not exhibit appreciable dif- ferences from those of isothermal simulation. Experimental Results. Isothermal experiments at 10238-1273 K and atmospheric total pressure were con- ducted in the reactor cell schematically shown in Figure 11. The cell consisted of an YSZ tube of 16-mm i.d., 19.5- mm o.d., open at both ends and enclosed in a 22-mm-i.d., 25-mm-o.d. quartz tube. The CH,-NHg mixture was flowing in the annulus between the YSZ and the quartz tube while the inside of the YSZ tube was exposed to air. Platinum electrodes (prepared from Engelhard A3786 Pt ink) was used for both anode and cathode. The cell was located in a furnace where the temperature was controlled within 2-3 °C. Reactants and products were analyzed by on-line gas chromatography. Details on the experimental apparatus can be found elsewhere (Kiratzis, 1991).
for adiabatic operation do not exhibit appreciable dif- ferences from those of isothermal simulation. Experimental Results. Isothermal experiments at 10238-1273 K and atmospheric total pressure were con- ducted in the reactor cell schematically shown in Figure 11. The cell consisted of an YSZ tube of 16-mm i.d., 19.5- mm o.d., open at both ends and enclosed in a 22-mm-i.d., 25-mm-o.d. quartz tube. The CH,-NHg mixture was flowing in the annulus between the YSZ and the quartz tube while the inside of the YSZ tube was exposed to air. Platinum electrodes (prepared from Engelhard A3786 Pt ink) was used for both anode and cathode. The cell was located in a furnace where the temperature was controlled within 2-3 °C. Reactants and products were analyzed by on-line gas chromatography. Details on the experimental apparatus can be found elsewhere (Kiratzis, 1991).
Figure 13. Effect of CHy/NHs3 ratio on rates of CO and H,0 in the experimental reactor cell for either gaseous or electrochemical oxygen. The operating current was 1 A, corresponding to an oxygen flow of 2.6 X 10° mol/s.
Figure 13. Effect of CHy/NHs3 ratio on rates of CO and H,0 in the experimental reactor cell for either gaseous or electrochemical oxygen. The operating current was 1 A, corresponding to an oxygen flow of 2.6 X 10° mol/s.
Figure 14. Effect of CH, conversion on HCN formation rate for various CH,/NHs ratios. The operating current was 39 mA, corre- sponding to an oxygen flow of 1 X 10-7 mol/s.
Figure 14. Effect of CH, conversion on HCN formation rate for various CH,/NHs ratios. The operating current was 39 mA, corre- sponding to an oxygen flow of 1 X 10-7 mol/s.

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References (23)

  1. Cowans, B. A.; Jurman, K. A.; Delgass, W. N.; Li, Y. Z.; Reifenberger, R.; Koch, T. A. Scanning Tunneling Microscopy of Platinum- Rhodium Gauze HCN Catalysts. J. Catd. 1990,125, 513.
  2. Debenedetti, P. G.; Vayenas, C. G.; Yentekakis, I.; Hegedus, L. L. Mathematic Modeling of Cross-Flow, Solid State Electrochemical Reactors. ACS Symp. Ser. 1984,237, 181.
  3. Grosz, F.; Zegers, P.; Singhal, S. C.; Yamamoto, 0. Proceedings of the Second International Symposium on Solid Oxide Fuel Cells, Athens; Commission of the European Communities: Luxembourg, 1991.
  4. Hasenberg, D.; Schmidt, L. D. HCN Synthesis from CHI and NH3 on Clean Rh. J. Catal. 1985, 91, 116.
  5. Hasenberg, D.; Schmidt, L. D. HCN Synthesis from C& and NH3 on Clean Pt. J. CUtUl. 1986,97,166.
  6. Hasenberg, D.; Schmidt, L. D. HCN Synthesis from C&, NHa and 0 2 on Clean Pt. J. C4td 1987, 104,441.
  7. Kiratzis, N.; The Synthesis of Hydrogen Cyanide ina Solid Electrolyte Fuel Cell. Ph.D. Thesis 1991, Tufta University.
  8. Kiratzis, N.; Stoukides, M. The Synthesis of Hydrogen Cyanide in a Solid Electrolyte Fuel Cell. J. Electrochem. SOC. 1987, 134, 1925.
  9. Kiratzis, N.; Stoukides, M. Kinetics of the HCN Synthesis in a Solid Electrolyte Cell. J. C4td 1991,132, 257.
  10. Kirk-Othmer Encyclopedia of Chemical Technology, 3rd ed.; Gray- son, M., Ed.; Wiley: New York, 1978.
  11. Koberstein, E. Model Reactor Studies of the Hydrogen Cyanide Synthesis from Methane and Ammonia. Znd. Eng. Chem. Process Des. Deu. 1973,12,444.
  12. McKenna, L. A. Modeling of HCN Synthesis in a Solid Electrolyte Fuel Cell. M.S. Thesis 1992, Tufts University.
  13. McKenna, L. A.; Stoukides, M. Modeling of HCN Synthesis in a Solid Electrolyte Fuel Cell. Chem. Eng. Sci. 1992,47, 2951.
  14. Michaels, J. N.; Vayenas, C. G.; Hegedus, L. L. A Novel Crow-Flow Design for Solid-State Electrochemical Reactors. J. Electrochem. Sac. 1986,133,522.
  15. Pan, B. Y. K. Characteristics of Pt-Rh Gauze Catalyst and Kinetics of the HCN Synthesis. J. Catal. 1971,21, 27.
  16. Pan, B. Y. K.; Roth, R. G. Optimization of Yield through Feed Composition. Znd. Eng. Chem. Process Des. Dev. 1968, 7, 54.
  17. Satterfield, C. N. Heterogeneous Catalysis in Practice; McGraw- Hilk New York, 1980.
  18. Schmidt, L. D.; Luse, D. Physical and Chemical Characterization of Platinum-Rhodium Gauze Catalysts. J. Catal. 1971,22,269.
  19. Schmidt, L. D.; Hansenberg, D.; Schwartz, S.; Papapolymerou, G. A. Surface Reactions on Clean Platinum and Rhodium at Low and High Pressures. ACS Symp. Ser. 1985,288, 177. Ind. Eng. Chem. Res., Vol. 32, No. 9, 1993 1913
  20. Stoukides, M. Applications of Solid Electrolytes in Heterogeneous Catalysis. Znd. Eng. Chem. Res. 1988,27,1745.
  21. Suarez, M. P.; Loffler, D. G. HCN Synthesis from C& and "8 at Atmospheric Pressure. J. Catal. 1986,97, 242.
  22. Vayenas, C. G.; Debenedetti, P. G.; Yentekakie, I.; Hegedus, L. L. Cross-Flow, Solid State Electrochemical Reactors: A Steady State Analysis. Ind. Eng. Chem. Fundam. 1985,24,316.
  23. Waletzko, N.; Schmidt, L. D. Modeling Catalytic Gauze Reactors: HCN Synthesis. AZChE J. 1988,34, 1146.

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