Mass transfer advantage of hierarchical structured cobalt‐based catalyst pellet for Fischer–Tropsch synthesis

Abstract

The low effectiveness factor of catalyst pellet caused by high internal diffusion limitation is a common issue in fixed-bed reactor. Nevertheless, hierarchical structured catalyst provides a promising solution for the contradiction between reaction activity and diffusion efficiency in large catalyst pellets. Herein, we studied the effect of pore structure parameters of the meso-macroporous catalyst on Fischer-Tropsch synthesis performances through experiment and pellet scale reaction-diffusion simulation.The pellet simulation firstly elucidated the reason for the significant improvement on activity and product selectivity for the meso-macroporous catalyst observed in our experiment. Further optimization via pellet simulation indicated the critical influences of wax filling degree and that the perfect matching between reaction and mass transfer rates by increasing macropore size and adjusting porosity within pellet enables the C 5+ space-time yield to the maximum. This work could provide a theoretical guideline for the engineering design of the hierarchical structured catalyst pellet.

Revealing the Effect of Mass Transfer on Direct Dehydrogenation of Ethylbenzene Catalyzed by Phosphorous‐doped Boron Nitride: Comparative Study

“…In addition, the existence of mesopores could effectively avoid the blockage of intermediates in the smaller micropores, so as to obtain the excellent activity and selectivity. [22][23] Although m-PBN-48 powder exhibited satisfying performance in the above discussion, the activity still decreased after 8 h, which was similar to PBN-1.2. We observed in our experiments that the byproduct had a certain viscosity, which might lead to the aggregation of catalyst and decreased the surface utilization.…”

Elements of the Manufacture and Properties of Technical Catalysts

“…These mass and energy transfer processes at the particle scale can mask the intrinsic rates and modify the overall reaction rates . However, they are rarely studied in technical catalysts …”

“…331 However, they are rarely studied in technical catalysts. 396 In what follows, we will discuss the above aspects for both packed bed reactors and fluidized bed reactors. catalyst have a specific pattern within a shell, Figure 95, and the pattern chosen for the bed depends on the reaction to be carried out.…”

Engineering an egg-shell structure for the Ag/SiO2 pellet catalyst for selective hydrogenation of dimethyl oxalate to methyl glycolate

“…Herein, we propose a type of egg-shell structure for the pellet Ag/SiO 2 catalyst concentrating Ag nanoparticles on the outer region of the SiO 2 pellet, by which the diffusion distance can be decreased and thus the intra-pellet transfer limitation alleviated according to the definition of the Thiele modulus. [14][15][16] Various ratios of the outer region concentrated with Ag to the whole region of the pellet catalyst (i.e., the thickness of the Agshell) are achieved by precisely controlling the synthesis procedure to systematically investigate the effects of the distribution of Ag within the pellet on the catalytic performance for selective hydrogenation of DMO to MG. Characterization results indicate that the similarly sized Ag nanoparticles distributed in the outer region of egg-shell catalysts exhibit similar electronic structures and adsorption properties.…”