Methods for preparing zeolites with the particle size of 50–200 nm using mechanical milling on bead mills (top-down approach) are analyzed. The milling can be described by a first-order rate equation, but mathematical models allowing prediction of the particle size and degree of crystallinity of zeolite after milling, based on the process parameters, are still lacking. The milling is accompanied by degradation of the zeolite lattice, leading to a decrease in the zeolite crystallinity and activity in catalytic reactions. Recrystallization and dealumination may be promising ways to restore the zeolite structure after milling; in this case, the choice of the conditions for such posttreatment is of crucial importance. Evolution of textural and acid properties of zeolites in the course of milling is considered, and the effect of milling conditions on the catalytic activity of zeolites in various reactions is discussed. The main outcome from a decrease in the size of zeolite catalysts is an increase in their activity and a decrease in the deactivation rate.

This research systematically investigates the influence of high-energy ball-milling (BM) parameters on the acidic and textural properties of zeolite Y. Among the BM parameters, the milling time (MT) exerted a more significant influence on the zeolite degradation than milling speed (MS), primarily affecting particle size and crystallinity. Milling produced nanozeolites with particle sizes ranging from 210 to 430 nm, and their activity was tested in the catalytic cracking of vacuum gas oil (VGO). The highest catalytic activity was observed for the zeolite with a particle size of 397 nm and a crystallinity of 75.9%: the VGO conversion was 69.0%, and the gasoline fraction yield was 33.9%, compared to the parent zeolite’s 62.7% and 22.1%, respectively. It was found that the activity of milled zeolites in catalytic cracking is determined by the accessibility of acid sites, which can be controlled by forming an optimal micro-mesoporous structure.

This review summarizes the current advances in the synthesis of polyoxyalkylene ethers and alkyl oxalates. It discusses the prospects for the application of these oxygenates as engine fuels and the methods for their structural modification to ensure effective control of their performance characteristics.

The study investigates catalytic conversion of polyethylene and polypropylene—in the form of 1–5 wt % solutions in vacuum distillate—to light olefins in the presence of a catalyst based on a mixture of zeolites Y and ZSM-5. The effects of reaction conditions and polymer pretreatment methods on the conversion degree and product selectivity are discussed. At 675°C quantitative conversion of the polyolefins was achieved, and the products mainly consisted of C₂–C₄ light olefins. The cracking of the polymer solutions enhanced the yield of light olefins compared to the pure vacuum distillate case, the enhancement reaching up to 9.9 wt %, including 5.2 wt % for propylene.

A number of metal sulfide catalysts were synthesized by hydrogen treatment of nickel, cobalt, copper, and iron sulfates supported on γ-Al₂O₃ (with a metal content of 5% and 10%). The resultant materials catalyze the decarbonylation of stearic acid to the corresponding higher olefins in the presence of hydrogen. The yield of target products decreases in the following order: Ni, Co > Cu > Fe. In the nickel and cobalt catalysts, X-ray diffraction (XRD) analysis identified interplanar distances (d-spacings) attributable to Ni₃S₂ and Co₉S₈. Such sulfides are likely responsible for their performance in decarbonylation. Hydrogen pretreatment time was found to be a factor that affects the activity of nickel and cobalt catalysts. XPS examination showed a decline in the sulfide sulfur to metal atomic ratio with an extension of hydrogen treatment time. The optimal time was found to range from 1 to 3 h.