Dissertation > Excellent graduate degree dissertation topics show

Studies on Kinetics of Ammonia Synthesis and Hydrogen Inhibition on Carbon-supported Ru Catalysts

Author: ZhangKuan
Tutor: LiuHuaZhang
School: Zhejiang University of Technology
Course: Industrial Catalysis
Keywords: Active Carbon Ruthenium-based Catalyst for Ammonia Synthesis Modified Temkin Kinetic Equation Inhibition by Hydrogen
CLC: TQ113.25
Type: Master's thesis
Year: 2008
Downloads: 20
Quote: 0
Read: Download Dissertation

Abstract


Promoted ruthenium-based catalysts are expected to be the second-generation catalysts for ammonia synthesis after fused-iron catalysts. Ruthenium-based catalysts are highly active ammonia synthesis catalysts which can be operated at high ammonia concentration, wide-range of hydrogen-nitrogen ratio, under low temperature, and low pressure. Dissociative adsorption of nitrogen is inhibited intensively by hydrogen on these catalysts. We have worked on ruthenium-based catalysts ammonia synthesis for several years. The performance of our catalysts have reached or exceeded the datas reported in the documents both at home and abroad, and according with the condition of industrialized catalysts. It is necessary for the design and operation of ammonia synthesis reactor using Ru/C catalyst to study and propose the kinetic equation for ammonia synthesis on ruthenium-based catalyst, and the relevant articles have not yet been seen at home. The phenomenon of hydrogen inhibition was studied to provide the theoretical basis for improving the activity of ammonia synthesis catalysts.The kinetics experimental data on Ba-Ru-K/AC catalyst for ammonia synthesis has been tested under industrially relevant reaction conditions (T =350-450℃, P = 10 MPa, H2/N2 = 1.0, 1.5, 2.0, 2.5, 3.0, Sv = 60000 -180000 h-1) in a fixed-bed reactor. Considering the suppressant effect of H2 and NH3 adsorption on N2 adsorption, the modified Temkin equation has been obtained by adding of H2 and NH3 adsorption terms. Optimized kinetic model parameters of n,α, w1 and w2 are 1, 0.15, 0.5 and 1.4, respectively. Based on this, the experimental datas have been fitted by using four-order Runge-Kutta numeric integration and complex method. The results indicates that a dependable kinetic model can be obtained by adding the H2 and NH3 adsorption terms to the Temkin equation. Linear fitting with the Arrhenius and Van’t Hoff equation shows the kinetic and thermodynamic parameters of k, KH2 and KNH3, i.e. the activation energy of ammonia synthesis reaction is 90.2 kJ/mol, which is higher than that of iron-based catalyst, namely, the activation energy barrier of N2 dissociative adsorption on Ru was far lower than either the traditional magnetite-based catalyst or wustite-based catalysts, and the heat of hydrogen adsorption was 76.2 kJ/mol. These data confirm that the adsorption of hydrogen on the Ba-Ru-K/AC catalysts is strong, which intensively inhibited the dissociative adsorption of nitrogen. The modified Temkin equation can be used for the design and operation of ammonia synthesis reactor based on Ru/C catalyst.Research shows that, outlet ammonia concentration doesn’t increase with increasing of pressure on carbon-supported Ru catalysts under low temperature（lower than 400℃）. This phenomenon is inconsistent with basic thermodynamic and kinetic theory of ammonia synthesis, and Temkin’s reaction kinetic theory for iron-based catalysts.Effect of promoter on the hydrogen inhibition for ruthenium-based catalyst for ammonia synthesis was studied. The results indicate that alkali and alkali earth metal and acidic promoters as vanadium enhance the hydrogen inhibition, while acidic promoters such as molybdenum and rare earth such as lanthanum could decrease the hydrogen inhibition.In summury, the present study shows that the kinetics study of ammonia synthesis and hydrogen inhibition on a carbon-supported Ru catalyst is of great theoretical and practical significance.

Related Dissertations

  1. Cefotaxime sodium simulated pharmaceutical wastewater treatment method,X703
  2. Regeneration Method and Process Design of Waste Activated Carbon of Glycine Production,X703
  3. Study on Treating the Coking Waste Water by Flocculation-absorption Process,X703
  4. In Different Pressure an Experimental Study on Migration of Radon,TL81
  5. Research on the Optimization of Ozone-biological Active Carbon Treatment,TU991.2
  6. Application of drug-loaded nano- carbon line chemotherapy for colorectal cancer lymph node targeted mice,R735.34
  7. Removal Efficiency of Lindane from Water Onto Novel Hybrid Lipid Materials,X703
  8. Study on Polythionphene/Polyaniline/Active Carbon Composites as Electrode Materials in Supercapacitors,TM53
  9. Study on Drilling Waster Water Advanced Treatment Technique for Dagang Oilfield,X703
  10. Study on the Refining Technology of Inulin,TQ914.1
  11. Studies on Preparation of Mesoporous Active Carbon from Corncobs and Its Applications,TQ424
  12. Study on Process of Inositol from Maceration Water of Corn,S513
  13. The Influence Factors on Absorption of SO2 by Activated Carbon,X701.3
  14. Methodology Studies of Inspection and Elimination of Pyrogen in Polysaccharopeptide of Coriolus Versicolor (PSP),R284
  15. Investigation and Application on the Treatment Technology for Dry-spun Polyacrylonitrile Fiber Wastewater,X703
  16. Preliminary Study of Concentrating Coalbed Methane by Adsorption,TD842
  17. A Study on Character Analysis and Debugging of Pretreatment Process of Sewage as Feed Water for Electricity Boiler,X703
  18. The Pharmacokinetics Properties of ACNP-MMC in Intraperitoneal Chemotherapy and the Course Behavior of the Carrier and Its Secretion from the Body,R735.2
  19. Study on the Treatment of Organic Wastewater Using RBC,X703.3
  20. Supports research on the impact of large -capacity capacitor performance,TM53

CLC: > Industrial Technology > Chemical Industry > Basic inorganic chemical industry > Ammonia and ammonium salt industry > Ammonia Industry > Machinery and equipment
© 2012 www.DissertationTopic.Net  Mobile