Acid-Modified Natural Bauxite Mineral as a Cost-Effective and High-Efficient Catalyst Support for Slurry-Phase Hydrocracking of High-Temperature Coal Tar

In this paper, we present a novel kind of supported Mo catalyst for hydrocracking high-temperature coal tar (HTCT), a byproduct of coal carbonization/gasification that has an abundant supply and is considered as a potential feedstock to refineries in the future. The catalysts are featured by their supports derived from a natural bauxite that has a low price and abundant reserves in the earth. The natural bauxite was modified via acid treatments with different acids (i.e., HCl, H₂C₂O₄, H₃PO₄, HNO₃, and H₃BO₃), and different supports were obtained. The physicochemical properties of the supports were systematically characterized, and the slurry-phase hydrocracking performance of the corresponding catalysts was assessed in a batch autoclave reactor. The results show that the modifications of the calcined natural bauxite with both HCl and H₂C₂O₄ yield two supports with an enlarged specific surface area and pore volume and enhanced acidity as a result of the leaching of Fe₂O₃ and the enrichment of Al₂O₃. Such characteristics are responsible for the outstanding catalytic performance of the derived catalysts. Moreover, the bauxite-derived support can reduce the total catalyst cost by 50–60% compared to a conventional γ-Al₂O₃ support. Our success provides an economic and effective catalyst for refiners to convert unconventional heavy feedstocks to value-added products

A Quasi-Solid-Phase Approach to Activate Natural Minerals for Zeolite Synthesis

Synthesis of zeolites or zeolite/clay composites from natural aluminosilicate minerals has received extensive attention because of its great usefulness in greening the zeolite manufacturing process, in which effective activation of natural aluminosilicate minerals is crucially important. Herein, we present an energy saving and green approach, the quasi-solid-phase activation method, to efficiently destruct the natural minerals under the conditions of a temperature as low as 100 °C and an activation time as short as 30 min. Our strategy consists of the following three steps: (1) preparation of a mixture of a natural kaolin mineral, NaOH, and water by kneading, (2) extruding of the mixture into sticks, and (3) low-temperature calcination of the stick, featured by the combined use of mechanochemical actions. The results showed that 84.7% Si species and 69.0% Al species in the kaolin mineral underwent a large degree of depolymerization in the kneading and extruding steps, and following calcination at 100 °C resulted in the complete depolymerization of the kaolin mineral to monomer orthosilicate anions (Q⁰) and tetracoordinated aluminum (Al^IV) species, which are highly active silica and alumina sources for synthesizing aluminosilicate zeolites. Using the activated kaolin mineral as a starting material, pure-phase NaY and NaA zeolites have been successfully synthesized

Origin of the Robust Catalytic Performance of Nanodiamond–Graphene-Supported Pt Nanoparticles Used in the Propane Dehydrogenation Reaction

Nanocarbon-supported Pt nanoparticles (NPs) were prepared and tested for the propane dehydrogenation reaction (PDH). The nanocarbon support is composed of a nanodiamond core and a defective, ultrathin graphene nanoshell (ND@G). The Pt/ND@G catalyst experienced slight deactivation during the 100 h PDH test, while the Pt/Al₂O₃ catalyst showed severe deactivation after the 20 h PDH test. Pt NPs exhibited superior sintering resistance versus that of the ND@G support. This particular support structure of ND@G allows electrons on the defects to transfer to the Pt NPs, leading to a strong metal–support interaction, which significantly prevents Pt NP sintering and promotes the desorption of electron-rich propylene. This electron transfer mechanism was also confirmed by a CO catalytic oxidation test