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Optimization of Synthesis Method and Operational Improvement of High Temperature Water-gas Shift Catalyst

Eshaghian, Razieh | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47863 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Baghghalha, Morteza; Kazemeini, Mohammad; Bahmani, Mohsen
  7. Abstract:
  8. The water-gas shift reaction, as a vital reaction in industry especially as a source of hydrogen for the manufacture of ammonia, is influential for all of the scientists and researchers in chemical engineering all around the world. In this research, high temperature water-gas shift (HTS) catalysts were investigated in order to study synthesis parameters and improvement of their performance and catalytic activity. The two catalyst categories; non pre-active and pre-active (magnetite-based samples, not requiring a reduction step prior to use) were prepared by co-precipitation method, using chloride, sulfate and nitrate metal (Fe, Cr, Cu) precursors and NaOH as precipitating agent (the aging time were 90 and 45 min). All of the catalysts are characterized with XRD, BET and TPR testes, and operating conditions of the activity tests are selected in a matter of this fact that the conversion of CO (37.54%) should be far enough from the equilibrium conversion of CO (88.6%). The comparison of pre-active and non pre-active samples revealed that this method is leaded to porous, fine crystallite size (dcF=dcP<10nm) and higher specific surface area. Furthermore, the reduction of H2 consumption in TPR analyses of pre-active catalysts showed that the active phase of iron oxide ( Fe3O4) is obtained. This research turned out that the aging time is not influential in performance of catalysts, moreover, the catalysts which are produced by sulfate precursors (in both pre-active and non pre-active methods ) have more catalytic activity in comparison of industrial samples; 49.13%, 41.19%, 59.09%, 53.55%, 53.72%, 54.65%, 53.86% for HTS-CTK, HTS-C12, HTS-1A(1) and 1A(2), HTS-PA-1B(1), PA-1B(2) and PA-1B(3) respectively. However, in the catalysts which are produced by chloride precursors (in both pre-active and non pre-active method), the undesirable features like lack of enough reduction, inadequate thermal stability and reduction of active surface area because of sintering are caused to decrease in catalyst performance; 11.34%, 13.25%, 3.05% and 7.61% for HTS-2A(2), HTS-PA-2B(1), PA-2B(2) and PA-2B(3) respectively
  9. Keywords:
  10. Aging ; Co-Precipitation ; Water Gas Shift (WGA)Reaction ; Pre-Active

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