The sulfidation process of porous zinc oxide sorbent with hydrogen sulfide can be described in five steps after external mass transfer and pore diffusion. They are surface adsorption of hydrogen sulfide gas on zinc oxide sorbent and dissociation of the gas molecule on the sorbent surface, followed by reversible surface reactions, sulfide ion migration under the surface, and sulfidation penetration into the solid crystallite. On the basis of the understanding of this chemistry, an empirical rate law for the intrinsic kinetics of the sulfidation process was derived in this study. Kinetics modeling results using this reversible, adsorption, and ion-migration (RAIM) model were found, consistent with selected experiments of single-particle sulfidation. Modeling results were also comparable with several well-defined sulfidation models in the literature. The intrinsic kinetics of a porous ZnO sorbent G-72E were measured in a microflow packed column and calculated using the RAIM model, using a finite difference approach. The effective pore diffusivity of gaseous hydrogen sulfide in the porous zinc oxide pellet was calculated using the general process modeling system (gPROMS). Finally, design calculation for a full-scale packed desulfurizer was performed using the gPROMS distributed reactor model. Case studies were presented for hydrogen sulfide removal from natural gas in a simulated fuel-processing train for syngas production.

Based on the water gas shift (WGS) catalytic mechanism on precious metal catalyst, a Langmuir–Hinshelwood (LH) kinetics model was derived for the operating conditions of syngas from natural gas reforming at near-ambient pressure. A power law kinetics model was also presented for comparative purpose. These two kinetics models were integrated in a dynamic distributed reactor model for design of full-scale WGS reactors for a natural gas fuel processing system. Modeling results indicated that the LH kinetics model gives predictions of reactor performance closer to the experimental data. Using the LH kinetics model, optimization of operating conditions for the high-temperature shift (HTS) and low-temperature shift (LTS) reactors was also attempted.

On envoie a) l'echappement d'un moteur et/ou b) de l'air d'entree (11) a un generateur d'hydrogene (22) associe a un carburant diesel (18) afin de produire de l'hydrogene et un monoxyde de carbone (26) soit c) pour melanger avec le flux principal de l'echappement alimentant un convertisseur catalytique (28) soit d) pour regenerer une paire de pieges d'adsorption (35, 36) de NOx, ce qui permet de reduire les oxydes d'azote (NOx) de maniere a obtenir un echappement (29) de systeme dont la teneur en NOx est inferieure a 0,20 grammes/bhp/hr et la teneur en hydrocarbures non-methaniques est inferieure a 0,14 grammes/bhp/hr. Une unite de recuperation (52, 63) d'eau peut extraire de l'eau a partir de l'echappement ou de l'effluent des pieges de No afin d'humidifier l'entree d'air (11) a melanger avec le carburant. L'entree d'air (11) peut etre humidifiee dans un humidificateur a bulles d'air (72) recevant de l'eau provenant d'un condensateur (76) qui utilise l'air d'entree pour refroidir l'effluent des pieges de No.

Conversion of olefins over the zeolite Ferrierite (FER) has been investigated in the temperature range 300 to 500 degrees C. Fast irreversible adsorption of butenes at 350 degrees C, completely filling the micropores, is observed using a microbalance. In the skeletal isomerization of butenes at that temperature, rapid initial coke build up is observed which slows down after 100 hours on stream. In the same time period the yield of isobutene produced from 1-butene increases while by-product formation, i.e. oligomers, is reduced. Fresh FER leads to extensive scrambling of a (13)C-label during butene isomerization as deduced from GC/MS experiments, whereas spent FER does not give rise to scrambling. Carbonaceous deposits play an important role in modeling for activation/deactivation of FER for olefin conversion. These deposits are initially involved in oligomerization and cracking reactions and their aromatisation leads to coverage of the external surface of the crystallites - as deduced from XPS and TEM data - thus blocking pores and leading to a slow overall deactivation. The stability of FER in olefin processing is further demonstrated for olefin aromatisation at 500 degrees C.