Takashi Kameoka

Sulfur-tolerant Pd-Pt/Yb-USY zeolite catalysts used to reformulate diesel oils

Abstract Bimetallic Pd-Pt catalysts supported on ytterbium-modified ultrastable Y (USY) zeolite showed excellent hydrodesulfurization (HDS) and hydrodearomatization (HDA) activity as well as high stability when used to reformulate hydrotreated diesel oils; sulfur decreased from 263 to −1 . Modification of USY zeolite with ytterbium by impregnation decreased the number of strong acidic sites, while it increased the dispersion of the Pd-Pt phases, thus, possibly contributing to the increase in the nitrogen- and sulfur-tolerance and stability of Pd-Pt/Yb-USY zeolite catalysts.

EXAFS study on the dispersion of molybdenum sulfide catalysts on γ-A12O3

The dispersion of molybdenum sulfide catalysts was characterized based on the lateral dimensions of MoS2 crystallites estimated by EXAFS. A new index ofN(Mo)/N(S), instead ofN(Mo), was used to estimate the average MoS2 size to minimize the contribution of the coexisting oxide or oxisulfide phase in the catalysts. EXAFS showed some advantages over other techniques, such as TEM or XPS.

Catalytic performance tests and deactivation behavior of Ni-W/Al2O3 catalysts developed for upgrading coal-derived liquids

Abstract A Ni W catalyst designed and developed for upgrading coal-derived liquids was used in 500 and 1000 h catalyst performance tests using coal-derived kerosene and gas oil, respectively. The catalyst showed considerable improvement in hydrodenitrogenation (HDN) and hydrogenation (HY) activities and less initial deactivation as compared to commercial catalysts. The catalysts used for the catalyst performance tests were characterized to clarify catalyst deactivation behavior. Precise characterization of the used catalysts by means of X-ray photoelectron spectroscopy, X-ray absorption fine structure (EXAFS and XANES), and transmission electron microscopy revealed that crystal growth of WS 2 -like structures and changes in the sulfided states and in the local structure of tungsten on the catalysts occurred during the upgrading reaction. These findings gave new insights for improving catalytic activity and the life of the newly developed catalyst.

Catalyst design and development for upgrading aromatic hydrocarbons

Abstract Background and strategy of catalyst development for upgrading aromatic hydrocarbons are intensively discussed. Originally prepared catalysts (hydrogenation and hydrocracking catalysts) were used for accelerated aging tests. Though each catalyst showed superior catalytic performance as compared to commercially available catalysts, a severe deactivation was observed on the hydrocracking (HC) catalysts. A new type of HC catalyst was designed and prepared, based on the understanding of catalyst deactivation. High silica NaY zeolites were synthesized using crown-ether. USY zeolites were then prepared by ion exchange, steaming and calcining. Surface properties and catalytic functions of well-crystallized USY zeolites were investigated to develop practical HC catalysts. The Ni–W catalyst prepared using the newly prepared USY zeolite showed a considerable improvement in the HC activity.

Deterioration of the “Ni–W–S” Phase of Hydroprocessing Catalysts during Reaction

The structures of fresh and aged Ni–W catalysts supported on Al2O3 have been analyzed by the XAFS techniques. The local structures around Ni and W in the fresh catalyst were found to be basically the same as those around Ni and Mo, respectively, in Ni–Mo catalysts. For aged catalysts, apparent increases in the coordination numbers of S and W around W were observed relative to the fresh catalyst. The local structure around Ni dramatically changed after aging for 950 h. These results suggest that WS2 slabs grow in the lateral direction during the reaction and that Ni atoms are released from the edge sites of the WS2 slabs.

Catalyst design and development for upgrading hydrocarbon fuels

Abstract Hydrogenation and hydrocracking catalysts were designed and synthesized based on findings from catalyst characterization and model reactions. Two types of the synthesized catalysts were then tested using two stage upgrading of unconventional feedstocks. The causes of catalyst deactivation were studied in order to prepare a practical catalyst with a long life.

Two stage upgrading of middle and heavy distillates over newly prepared catalysts

Abstract Two kinds of catalysts, designed and prepared based on fundamental research, showed superior catalytic activities in the first-stage and second-stage upgrading of unconventional middle and heavy distillates, resulting in considerable improvements in overall activity (hydrogenation, HDN, HDS and hydrocracking) and initial deactivation of two stage upgrading.

Characterization of Ni-W/Al2O3 Catalyst Used in Coal Liquid Upgrading

Publisher Summary This chapter focuses on the analysis of X-ray absorption fine structure (XAFS) in which multiple scattering effect considered to obtain more precise information on the local structure around Ni and W in the catalyst. A highly active Ni-W/Al 2 O 3 catalyst is developed to upgrade coal-derived liquids that are characterized using XAFS method. Local structures around Ni and W in the fresh catalyst are basically the same as those around Ni and Mo, respectively, in Ni-Mo catalysts. The changes in the local structures around W and Ni on the catalysts showed that most of W occurs as WS 2 crystal and Ni as Ni 3 S 2 crystal. These results suggest that the catalytically active phase of Ni-W-S structure decompose into bulk single sulfides after use in the upgrading reaction of coal-derived liquids.

Zeolite Catalyst for Hydrocracking Coal-Derived Distillates: -Cleavage of naphthenic rings over zeolite catalysts-

Publisher Summary A new type of hydrocracking catalyst is designed for the second-stage upgrading. Optimizations of catalyst supports and metal loadings of hydrocracking catalysts are performed to develop new types of hydrocracking catalyst with high activity and long life. Because unconventional feedstocks contain large amounts of aromatics and hetero-atoms, the insufficient hydrocracking of aromatics occurs in a one-stage process. Conversion of polyaromatic hydrocarbons in middle and heavy distillates to lighter fractions using hydrocracking proceeds through two fundamental steps. In the first step, the aromatics are hydrogenated, and in the second step, these reduced aromatics are hydrocracked. Two kinds of catalysts, each possessing higher hydrogenation or hydrocracking activity are required for the two-stage upgrading. In the course of research and development of the hydrogenation and hydrocracking catalysts developed a Ni-W/AI2O3 catalyst for the first-stage upgrading of coal-derived liquids.

Highly Active Ni-W/Al2O3 Catalyst for Upgrading Unconventional Feedstocks

Abstract A highly active Ni-W/Al 2 O 3 catalyst was developed to upgrade coal-derived liquids. Compared to conventional Ni-Mo catalysts, the Ni-W catalyst was found to have higher hydrogenation and lower hydrocracking activities. Because of these properties, the Ni-W catalyst showed high hydrodenitrogenation activity and slow deactivation for feedstocks with a large amount of catalyst poisons.