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The ethylene hydrogenation reaction was investigated in a kinetic turbo reactor and a one-sided single-pellet reactor. An empirical kinetic expression was fitted to experimental results taken from the turbo reactor, and the gas compositions at the catalyst centers were measured for three different pore structures by means of the single-pellet reactor. A bimodal pore model was developed and applied to the computation of the gas composition profiles inside the three pore structures. The calculated results were compared to the measurements. A distinct influence of the pore structures on the gas fluxes and concentration profiles inside the pores could be detected which demonstrates that the proper choice of the pellet pore structure is of importance for a high conversion. [ABSTRACT FROM AUTHOR]

The effect of catalyst pore structure on n-butane oxidation to maleic anhydride in a fixed-bed reactor was investigated by numerical simulations. The micro- and macro-pore model of Wakao and Smith was applied to model the diffusion–reaction inside the catalyst pellet. The studied pore structure parameters were macro-pore porosity, mean macro-pore diameter and mean micro- pore diameter. A fixed-bed reactor was simulated with a detailed two-dimensional heterogeneous model under typical industrial conditions. Simulation results have demonstrated that the reactor performance is sensitive to the chosen pore structure parameters especially macro-pore porosity and mean micro-pore diameter. A bi-modal catalyst pellet with bigger macro-pores and smaller micro-pores is favored to achieve higher yields of maleic anhydride. This work highlights the potential of improving this process by pore structure optimization. [ABSTRACT FROM AUTHOR]

Designing the pore network structure is an effective approach to improve the performance of industrial catalyst particles, although it receives less attention than designing catalytic surfaces or active sites. This work presents a first example of the optimization of catalyst pore network structures in the presence of deactivation by coke formation, using a three‐dimensional pore network model. Propane dehydrogenation in a Pt‐Sn/Al2O3 catalyst particle is taken as the model reaction system. Catalyst particles with unimodal and bimodal pore‐size distributions are investigated, both being commonly used in industry. The porosity, connectivity, pore size, and their spatial distributions are optimized under two separate assumptions: constant intrinsic activity per unit catalyst weight and constant intrinsic activity per unit internal surface area. The optimized catalyst shows up to 14‐fold improvement in the time‐averaged propene formation rate, when compared to a benchmark catalyst. This significant improvement is primarily because of reductions in diffusion resistance and pore blockage. [ABSTRACT FROM AUTHOR]

• A continuum model is developed to simulate DRM in catalyst pellets. • The preferred pore diameter is 300 nm, and the optimal porosity is 0.51–0.64. • The bidisperse catalyst is 56–175% more active but uses 10–18% less catalyst. • Engineering pore structure is needed in the design of DRM catalyst pellets. Enhancing the utilization and activity of catalytic materials is crucial in designing catalysts for industrial use. This work achieves these performance enhancements in Rh/Al 2 O 3 catalyzed dry reforming of methane (DRM) at the catalyst pellet level, through engineering catalyst pore network structure. A continuum model, describing the coupled mass, heat transfer and reactions, is developed to optimize the monodisperse and bidisperse catalyst pellets under different temperatures, pressures, and CH 4 /CO 2 ratios. The results show that the preferred pore diameter for the monodisperse catalyst and macropore diameter for the bidisperse catalyst are all 300 nm, above which Knudsen diffusion is not important. Besides, the optimal porosities for the monodisperse and bidisperse catalysts are in the ranges of 0.51–0.59 and 0.61–0.64, which is the result of the trade-off between diffusion and reaction. The optimal bidisperse catalyst can be 56–175% more active but uses 10–18% less catalyst materials when compared to the optimal monodisperse catalyst with the same mesopore size, indicating the great advantage of introducing the optimal macroporosity into mesoporous catalyst pellets for DRM. These results should serve to guide the rational design of industrial catalyst pellets. [ABSTRACT FROM AUTHOR]

• We propose a pore network model able to aid the design of Claus catalysts. • The deactivation and regeneration of Claus catalyst particles are probed. • Multiple steady states are found where capillary condensation of sulfur occurs. • Catalyst particle structures strongly affect the performance of Claus catalysts. • A bimodal catalyst particle shows higher activity and uses less catalytic material. A pore network model is proposed to study the deactivation of Claus catalysts caused by sulfur condensation, as well as the corresponding regeneration. This model allows to describe the coupled reaction, diffusion, and sulfur condensation from a single pore to a catalyst particle. The results show that the deactivation branch of apparent activities is well above the regeneration branch in the temperature and pressure ranges where capillary condensation of sulfur occurs. This phenomenon of multiple steady states can be attributed to the inconsistent contents of liquid sulfur in the catalyst particle when changing temperature and pressure in different directions. The catalyst particle shape and pore network structure directly influence diffusion resistance, internal surface area for reaction, and sulfur condensation, and subsequently pass these influences on to the apparent activity. This work should provide a proper model and some useful guidelines for the design of catalyst particles for the Claus reaction. [ABSTRACT FROM AUTHOR]