Teruo Suzuka

Hydrodesulfurization activity of CoMo and NiMo supported on Al2O3–TiO2 for some model compounds and gas oils

Catalytic activities of Al2O3–TiO2 supporting CoMo and NiMo sulfides (CoMoS and NiMoS) catalysts were examined in the transalkylation of isopropylbenzene and hydrogenation of naphthalene as well as the hydrodesulfurization (HDS) of model sulfur compounds, conventional gas oil (GO), and light cycle oil (LCO). Al2O3–TiO2 supporting catalysts exhibited higher activities for these reactions except for the HDS of the gas oil than a reference Al2O3 supporting catalyst, indicating the correlation of these activities. Generally, more content of TiO2 promoted the activities. Inferior activity of the catalyst for HDS of the gas oil is ascribed to its inferior activity for HDS of dibenzothiophene (DBT) in gas oil as well as in model solvent decane, while the refractory 4,6-dimethyldibenzothiophene (4,6-DMDBT) in gas oil as well as in decane was more desulfurized on the catalyst. Characteristic features of Al2O3–TiO2 catalyst are discussed based on the paper results.

Residual oil cracking with generation of hydrogen: deactivation of iron oxide catalyst in the steam-iron reaction

Abstract The deactivation of iron oxide catalyst in residual oil cracking with generation of hydrogen was studied. This new process consists of two main stages: the cracking of residual oil and hydrogen generation resulting from the steam-iron reaction, and the reduction of the iron oxide catalyst. We found that the hydrogen-producing activity of the iron oxide catalyst declined during consecutive reduction and oxidation cycles. The aging rate was dependent on the reaction conditions. When the rate of oxidation was not fast enough to convert prereduced wustite (FeO) to magnetite (Fe3O4), the wustite accumulated and the activity declined. The accumulation of wustite is considered to induce the sintering of the catalyst. This hinders the free access of the reaction gases and reduces the rate of the iron oxide-gas phase reaction. We concluded that it is essential to balance the stoichiometry of the reduction and oxidation to prevent the deactivation of the catalyst.

Catalytic behavior of platinum ion-exchanged zinc-aluminosilicates in n-pentane aromatization

Abstract The n-pentane aromatization over platinum ion-exchanged zinc-aluminosilicate was investigated. The deactivation of the catalyst decreased with increasing density of strong acid sites of the zeolites. X- ray photoelectron spectrometry studies and platinum dispersion measurements revealed that platinum atoms became more cationic and were located inside the zeolite pores when platinum was loaded onto zeolites with a higher strong acid site density. Platinum atoms were less cationic and tended to migrate to the external surface where they aggregated when platinum was loaded onto zeolites that had a lower strong acid site density. The migration and aggregation of platinum were assumed to cause a rapid decline in catalyst activity.

Residual Oil Cracking with Hydrogen Generation

The cracking of residual oils with simultaneous hydrogen generation has been carried out. In this process, the by-product coke deposited on the surface of the catalyst is partially oxidized in the regenerator with the formation of carbon monoxide, and the heat of reaction generated is utilized for cracking of the feed. Carbon monoxide works as a reducing agent for converting triiron tetraoxide (Fe3O4) in the catalyst to ferrous oxide (FeO), which in turn, is converted to Fe3O4 by its reacting with steam to generate hydrogen. A large amount of hydrogen can be produced from the process without coke formation. The amount of hydrogen production is large enough to desulfurize the product distillates produced from the process. Feasibility of the process for upgrading residual oils has been confirmed by the results of 0.6 BPD- and 250 BPD- pilot plants.

Effect of Reaction Temperature on Cracking of Residual Oil over Nickel Oxide Ore

Kuwait vacuum residue was cracked over a nickel oxide ore catalyst and over porcelain Raschig rings at 450-650°C, and the yields and properties of the cracked products were investigated. The gas yield increased and the yield of Fraction R (boiling point 510°C+) decreased with increase in the reaction temperature, while coke yield remained almost constant. Higher yields of hydrogen and distillates were observed over the catalyst than over Raschig rings. It was inferred that the cracking and coking activities of the catalyst were due to the partially reduced state of the iron and nickel oxides which were reduced by hydrocarbon vapors during the cracking reaction. The cracked oil obtained over the nickel oxide ore catalyst had high contents of C10-C15 linear α-olefins.