Our studies of catalytic cracking catalysts investigated the preparation and function of novel matrices to develop various hierarchical catalysts. The introduction of mesoporous components of matrix into the catalyst increased the activity and modified the function of zeolite. The gel skeletal reinforcement method was effective to produce zeolite-containing hierarchical catalysts, with increased activity and product selectivity. The Curie point pyrolyzer was effective to evaluate the catalysts by analyzing the catalytic cracking of huge molecules of vacuum gas oil (VGO), soybean oil (SBO) and low-density polyethylene (LDPE). Simultaneous generation of zeolite and mesoporous silica generated uniform hierarchical catalysts, which were effective for the selective formation of valuable products such as p-xylene in catalytic cracking of LDPE. As a combined process for hydrocracking and catalytic reforming, dehydrocyclization-cracking of SBO and fatty acid methyl ester (FAME) was developed to form hydrogen and aromatics under low pressure of less than 1.0 MPa using zeolite-Al₂O₃ composite catalysts-supported PtNiMo hydrocracking catalysts. Both PtNiMo and PtCoMo catalysts could form liquid fuels at H₂ pressure of lower than 1 MPa. Zn- or Ga-exchanged H-ZSM-5 and matrix Al₂O₃ composite catalytic reforming catalysts were prepared to make aromatics through dehydrocyclization of n-pentane. The presence of matrix Al₂O₃ increased the selectivity for aromatics and dimerization of C2-C4 olefins by the Diels–Alder reaction on reduced Zn and Ga species and subsequent dehydrogenation formed benzene, toluene and xylene.

An oxidation system for dibenzothiophene consisting of molecular oxygen, aldehyde, and transition metal catalysts in hydrocarbon solvents was evaluated using both batch and flow reactors. The effects of solvents and the presence of nitrogen-containing compounds were examined in the reaction using the batch reactor. The properties of the hydrocarbon solvents significantly affected the reaction rates; hydrogen donor solvents such as tetralin disturbed the reaction, whereas oxidation proceeded rapidly in solvents with no donatable hydrogens such as benzene. The presence of pyrrolic compounds disturbed the reaction, whereas pyridinic compounds had rather small effects. Using a continuous flow type reactor, the oxidation of dibenzothiophene could be carried out and the combination of MnCl₂ or CoCl₂ and HY-zeolite showed the optimum catalytic performance. The types of solvents and presence of nitrogen-containing compounds also affected the reaction rate drastically, as both hydrogen donor solvents and nitrogen-containing compounds such as quinoline disturbed the reaction. Likely mechanisms are discussed based on the effects of the solvents and nitrogen-containing compounds.

Extractive desulfurization (EDS) of model diesel fuels was examined using several polar solvents such as nitriles, esters, sulfoxides, amides, and ureas. EDS of 49-86 % of dibenzothiophene in model diesel fuels (10 g) was performed using these solvents (5 g). Among the solvents, amide solvents such as 1-methylpyrrolidin-2-one (NMP) achieved the best EDS. Relationships between the extractability and the characteristics of solvents were evaluated. The results indicated that polarity of the solvents, i.e., dipole moments, strongly affects extraction yield. Relationships between the structures of the sulfur compounds and extraction efficiency were also investigated. The results suggested that highly condensed aromatic compounds have high extraction yields, whereas methyl group substitution caused significant decreases. Finally, the partition equilibria were investigated. Amide solvents showed behavior that deviated from the normal partition equilibria.

Removal of harmful phenol from exhaust gases emitted during plastic pyrolysis requires an effective catalyst for phenol steam reforming under dilute conditions. Sr addition to Ni/Al₂O₃ catalyst, a common steam reforming catalyst, improved the catalytic activity for hydrogen production. Ni/Sr/Al₂O₃ catalyst, in which Ni was loaded onto Sr/Al₂O₃, was more effective than Sr/Ni/Al₂O₃ catalyst, in which Sr was added to a Ni/Al₂O₃ catalyst. In addition, Ni–Sr/Al₂O₃ catalyst, in which Ni and Sr were co-loaded onto Al₂O₃, showed similar effects but was inferior to Ni/Sr/Al₂O₃. The optimum Sr/Ni molar ratio was 1 for the Ni/Sr/Al₂O₃ catalysts. The effect of Sr addition was to increase the basic adsorption sites of phenol and to modify the electronic state of the reaction site due to the electron donation effect from Sr to Ni. The combination of these two factors improved the catalytic activity.

Torrefied biomass pellets (TBP) may carry the risk of spontaneous combustion during storage. Understanding the self-heating behavior and spontaneous ignition characteristics of TBP is important for the establishment of storage guidelines for TBP. This study conducted outdoor storage tests of approximately 1500 t of TBP and measured the temperature changes within TBP stockpiles. Spontaneous ignition tests of TBP, bituminous coal, and sub-bituminous coal were conducted using a quasi-adiabatic spontaneous ignition tester (SIT). The outdoor storage tests showed that the temperature of TBP stockpiles rose from 293 to 313 K in about 15 days. However, the SIT results did not match the findings of the outdoor storage test because TBP heated up more slowly than the bituminous coal. Therefore, this study revealed that the specific surface area must be considered when comparing TBP and coal in the SIT. Monitoring of temperatures over time and adequate actions are important when temperatures exceed 313 K during outdoor storage of TBP.