Synthesis and Mathematical Modelling of the Preparation Process of Nickel-Alumina Catalysts with Egg-Shell Structures for Syngas Production via Reforming of Clean Model Biogas

Abstract

For the work presented herein nickel catalysts supported on γ-alumina extrudates (Ni/Al) with an egg-shell structure were prepared, using a modified Equilibrium Deposition Filtration (EDF) technique. Their performance was compared, for the biogas dry reforming reaction, with corresponding Ni/Al catalysts with a uniform structure, synthesized via the conventional wet impregnation method. The bulk and surface physicochemical characteristics of all final catalysts were determined using ICP-AES, N2 adsorption-desorption isotherms, XRD, SEM, and TEM. A theoretical model describing the impregnation process for the EDF extrudates, based on the Lee and Aris model, was also developed. It was concluded that following specific impregnation conditions, the egg-shell macro-distributions can be successfully predicted, in agreement with the experimental results. It was shown that the Ni/Al catalysts with an egg-shell structure had a higher H2 yield in comparison with the ones with a uniform structure. The difference in catalytic performance was attributed to the improved surface and structural properties of the egg-shell catalysts, resulting from the modified EDF technique used for their preparation.

Adsorption of Nickel Ions on the γ-Alumina Surface: Competitive Effect of Protons and Its Impact on Concentration Profiles

“…Chu et al obtained eggshell profiles after contacting alumina solids (that were previously wetted with water only) with diluted nickel solutions at high initial pH in batch mode experiments . Eggshell profiles are especially beneficial in reactions with fast kinetics and strong diffusion limitations, as in Fischer–Tropsch synthesis, methane reforming, and partial oxidation. − …”

Advances in CO2 recycle to alcohols and ethers through hydrogenation

“…Challenges include CO 2 inertness, 3,74 complex reaction paths, 67 C-C coupling control. 72,74 The chemical stability of CO 2 makes it less reactive, demanding specific catalytic strategies. Several competing reactions occur during CO 2 hydrogenation, leading to a mixture of products (methanol, hydrocarbons) and reducing higher alcohol selectivity.…”

“…Precise control over carbon-carbon (C-C) coupling reactions is crucial for maximizing higher alcohol yield. 74 Catalytic advancements include Co-based catalysts, 3,67 Cu-based catalysts, 74 noble-metal catalysts, 72,73 and Mo-based catalysts. 72 Modified cobalt catalysts (Co-Co 2 C interfaces, Co-M alloys) show promise due to their CO adsorption and C-C coupling abilities.…”

Enhanced coke-resistant Co-modified Ni/modified alumina catalyst for the bireforming of methane

“…3 Biogas primarily contains two global warming gases, namely, methane (50-70%) and carbon dioxide (20-40%), with trace amounts of other gases such as hydrogen, ammonia, hydrogen sulfide, oxygen, and nitrogen. [4][5][6] The presence of impurities and the typical biogas composition is another obstacle to its application, depending on the feedstocks used, which should be free from impurities, including nitrogen, sulfur species, siloxanes, and ammonia. Also, anaerobic digestion with different reaction conditions can control biogas content ratios.…”