Date of Award


Degree Type


Degree Name

Doctor of Philosophy


This dissertation describes the study of the Pseudoadiabatic fixed-bed catalytic reactor for the one-step conversion of synthesis gas into gasoline using a bifunctional catalyst. The bifunctional catalyst allows to combine the thee steps of methanol synthesis, methanol dehydration and methanol conversion to gasoline, occurring in the adiabatic configuration of the Mobil MTG process, in one single reactor. Moreover, the use of the Pseudoadiabatic reactor offers good control of the temperature distribution, thermal symmetry and reduced parametric sensitivity for this very exothermic reaction.;The catalyst used in the context of this research was a bifunctional catalyst composed of a mixture of a methanol synthesis catalyst (ZnO-Cr{dollar}\sb2{dollar}O{dollar}\sb3{dollar}) and a ZSM-5 zeolite. It was found that the optimum formulation of the catalyst was: {dollar}-{dollar}63% Zn/Cr 0.08 weight ratio, calcined at 350{dollar}\sp\circ{dollar}C, {dollar}-{dollar}27% H-ZSM-5 zeolite, {dollar}-{dollar}10% Al{dollar}\sb2{dollar}O{dollar}\sb3{dollar} binder. It was also found that the catalyst reduction with diluted hydrogen (8% H{dollar}\sb2{dollar} {dollar}-{dollar}92% N{dollar}\sb2{dollar}) was a key factor in increasing the activity and the resistance to deactivation of the catalyst. The catalyst was characterized using different physical and chemical techniques (XRF, XRD, BET, TPR, XPS, IR).;A kinetic study of the synthesis gas conversion was performed in order to simulate the Pseudoadiabatic reactor unit. Three kinetic model equations, describing the rate of the synthesis gas conversion on the bifunctional catalyst, were considered to fit the data of the experimental runs performed in the Berty well-mixed reactor.;Several runs were performed in a continuous process development unit specially designed for assessing the viability of the Pseudoadiabatic operation design for this complex reaction system. It was observed that the Pseudoadiabatic regime was obtained in an important range of the following conditions: 2.4-16.9 {dollar}\ell{dollar} STP/min input flow, 350-380{dollar}\sp\circ{dollar}C inlet temperature, 20-34 atm total pressure, 0.73-1.4 H{dollar}\sb2{dollar}/CO ratio. Under the conditions studied, the liquid productivity was found to vary from 0.0035 to 0.0136 kg/hr while the selectivity to aromatics varied from 38.7 to 70.8% (wt% of aromatics in total hydrocarbons).;Furthermore, a comparison of the experimental results with a computer simulation of the process development unit was performed.;Finally, a global process assessment including mass and heat balances was performed using the HYSIM simulation software.



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