Kinetic modelling of the catalytic conversion of synthesis gas

Abstract

A kinetic study for the one‐step conversion of synthesis gas to gasoline on a ZnO–Cr2O3–ZSM‐5 catalyst is described. On this catalyst, three reactions are involved in the overall transformation of synthesis gas: the methanol synthesis, the conversion of methanol to hydrocarbons and the water–gas shift reaction. Under the operating conditions selected for the study, it was found that the water–gas shift was at equilibrium and the methanol was completely converted to hydrocarbons. Consequently, it was postulated that the kinetics of the limiting reaction step, the methanol synthesis on the ZnO–Cr2O3 component, was the one that controls the overall reaction rate. Three kinetic model equations describing the rate of synthesis gas conversion on the bifunctional catalyst, were considered to fit the data of the experimental runs performed in a Berty well‐mixed reactor. Those equations were derived under very special conditions where the methanol decomposition term could be neglected. It was also observed that in the kinetic equations a term involving the fugacity of CO2 was required to predict the rate properly. The catalyst deactivation was also taken into account in the analysis.

Recent Advances in Direct Synthesis of Value‐Added Aromatic Chemicals from Syngas by Cascade Reactions over Bifunctional Catalysts

“…In comparison with the Co‐based catalysts, Fe or other methanol synthesis catalysts are more favored for the production of aromatic monomers from syngas, although both catalysts have their own advantages and disadvantages. For example, WGS activity is quite problematic on those traditional methanol synthesis catalysts such as Cr–Zn, Pd–Zn, and Cu–Zn metal oxides as a result of an ample amount of CO 2 production in the range of ≈40−75 wt%, and hence very lower hydrocarbon formation (≈25 wt%) . Compared to the Cu–Zn and Pd‐based bifunctional catalysts, the Cr–Zn/HZSM‐5 or Zn–ZrO 2 /HZSM‐5 can transform completely the formed intermediates (oxygenates) to aromatics, which seems to be attributed to a combined acidic site effect of the HZSM‐5 and metal oxides (slightly acidic nature).…”

HZSM-5 Zeolites with Different SiO2/Al2O3Ratios. Characterization and NH3Desorption Kinetics

“…The present research is also a valuable complement to several studies initiated in 1987 and continued in recent years at the CREC Laboratories, The University of Western Ontario, by Hugo de Lasa’s research group. Examples of these successful studies include methanol conversion to gasoline, − syngas conversion to liquid hydrocarbons, − and desulfurization of gasoline. ,− …”