Mitsuyoshi Yamamoto

The influence of preparation methods on the pore structure of alumina

Abstract Structural characterization of eleven kinds of aluminas prepared by different methods was carried out by measurement of the adsorption of nitrogen, X-ray diffraction and scanning electron microscopy. Aluminas prepared using aqueous ammonia as precipitation reagent exhibited a single pore size distribution, the maximum being at a radius of about 20A, whereas aluminas prepared with urea exhibited a twin peaked pore size distribution, with maxima at radii of about 20Aand 50A. The pore structures of aluminas prepared from aluminium nitrate by pyrolysis and from sodium aluminate with carbon dioxide were similar to the former, while aluminas prepared by pyrolyses of aluminium isopropoxide and of aluminium trichloride had a pore structure similar to the latter. Based on scanning electron microscopy and nitrogen adsorption-desorption hysteresis loop observations, the crystallite structures of aluminas and pore structures were discussed in connection with the preparation methods employed.

Selective nuclear hydrogenation of naphthalene, anthracene and coal-derived oil over Ru supported on mixed oxide

Abstract The main objective of this paper is to investigate the possible ways to produce high-quality products for transportation fuels from heavy distillates. For this purpose, 0.1, 0.2, 0.5, and 1.0 wt% Ru, supported on three kinds of metallic oxide supports, Ru/Mn 2 O 3 ZnO, Ru/Mn 2 O 3 NiO and Ru/Mn 2 O 3 La 2 O 3 , were used as catalysts for selective nuclear hydrogenation of naphthalene, anthracene, and Canadian Battle River-coal-derived oil. The catalysts exhibited activity in the following order: Ru/Mn 2 O 3 NiO>Ru/Mn 2 O 3 ZnO>Ru/Mn 2 O 3 La 2 O 3 . The Ru/Mn 2 O 3 NiO catalyst showed the lowest exothermic temperature, corresponding to a decrease of differential pressure of hydrogen observed in the high-pressure DTA, and gave the largest H/Ru values among the catalysts determined by hydrogen chemisorption. The Ru/Mn 2 O 3 (0.19) NiO(0.81) among them showed the best performance for the reaction; it yielded 33 mol% of decalins from naphthalene and 49 mol% of perhydroanthracene from anthracene. The catalyst also converted 59 mol% of aromatic hydrogen to hydrogen at β- and γ-positions of aromatic hydrocarbons in the coal liquid. The temperature-programmed desorption (TPD) spectra of hydrogen and ammonia on the catalysts were measured to find the influence of acidity of supports for the catalytic activity. It was concluded that Ru on nonacidic support, which is Mn 2 O 3 NiO, showed the best performance, and a 0.1 wt% Ru loading on the Mn 2 O 3 NiO was sufficiently effective for the selective nuclear hydrogenation.

Catalytic behaviour of sulphate and sulphide in S-promoted iron oxide catalysts for liquefaction of bituminous coal and lignite

Abstract Catalytic activities of sulphate (S6+) and sulphide (S2−) for liquefaction of bituminous coal and lignite were studied. In addition, their catalytic activities in the presence of tetralin during liquefaction of both coals were also investigated. The specific catalysts used were FeS2 as a sulphide, and Fe2O3(SO4)2− and ammonium sulphate as sulphates. The liquefaction for different types of coals was carried out in the presence of these catalysts and tetralin as donor solvent under either 10 MPa of H2 or N2 initial pressure by using a 70 ml autoclave. The intrinsic activities of these catalysts were evaluated by the distribution of products obtained from tetralin during coal liquefaction. Catalyst Fe2O3(SO4)2− showed the highest activities for hydrogenation and hydrocracking of tetralin. FeS2 showed slightly lower activities. Ammonium sulphate showed activity only for dehydrogenation of tetralin. Also, both catalyst Fe2O3(SO4)2− and FeS2 showed significantly high activity for hydroliquefaction of coals and the ammonium sulphate was found to be inactive. Our results also indicated that the hydroliquefaction activity of catalysts occurs preferentially via reaction with molecular hydrogen rather than through participation of donor solvent.

Catalytic activity of sulphate for hydroliquefaction of coal by using diphenylether and diphenylmethane

The catalytic activity of sulphate found in S-promoted iron oxide catalyst was investigated using model compounds such as diphenylether and diphenylmethane. The formation of sulphate was carried out by addition of water in the S-promoted iron oxide system. The catalysts used were FeS2, Fe2O3/S, Fe3O4S, red mudS and FeSO4 of analytical reagent grade. Reaction was carried out in the absence and presence of water under H2 or N2 atmosphere. When diphenylether was reacted under H2 atmosphere, reaction products were found to be benzene and phenol, but unknown compounds with high boiling points were also found under N2 atmosphere. Diphenylmethane was converted to benzene, toluene, bibenzyl, triphenylmethane, anthracene and unknown compounds under H2 and N2 atmosphere. It was shown that sulphate clearly promoted radical formation from phenyl and benzyl groups by dehydrogenation and the radicals formed were polymerized to various higher volatile compounds under N2 atmosphere as well as under H2 atmosphere, atmosphere.

Mechanism for formation of sulphate in S-promoted iron oxide catalysts for coal liquefaction

Abstract The mechanism for the formation of sulphate and sulphides in sulphur-promoted iron oxide catalysts for coal liquefaction has been discussed. The catalysts used were FeS, FeS 2 and Fe 3 O 4 of analytical reagent grade, and iron (Fe 2 O 3 ) prepared by precipitation from ferric nitrate. These catalysts were reacted with sulphur in the presence of water under H 2 or N 2 at 10.1 MPa initial pressure. Distributions of the sulphur in the reaction system were complete made using i.r. XPS, XRD and thermal analysis measurements. Based on these experiments, it was found that ratios of sulphides (S 2− )/sulphates (S 6+ ) give important information on the mechanism. It was concluded that the sulphate and sulphides were formed simultaneously by the following equation: nS + 2 H 2 O = SO 2 + ( n − 1) H 2 S + (3 − n ) H 2 .

Behaviour of the FeOSH system under coal liquefaction conditions

Abstract The behaviour of the iron-sulphur system in the presence of water and hydrogen under coal liquefaction conditions has been investigated by using a high-pressure differential thermal analysis technique. The iron compounds used were Fe 2 O 3 , Fe 3 O 4 and FeS 2 . DTA was performed under 10.1 MPa (initial pressure) N 2 or H 2 , heating to 450 °C (2.5 °C min −1 ). Sulphate ions were detected by BaCl 2 addition to the product aqueous solution; sulphides were formed as gaseous and solid products. The results suggest that the catalytic behaviour of the sulphate and sulphides formed under the conditions employed must be considered for the iron-sulphur system in coal liquefaction.

Catalytic activities of sulphate and sulphide in sulphur-promoted iron oxide catalyst for coal liquefaction

Abstract The catalytic activities of sulphate (S6+) and sulphide (22−) in the liquefaction of Taiheiyo coal were investigated. The catalysts used were FeS2 as sulphide and (NH4)2SO4 and Fe2O3(SO4)2− as sulphates. Coal liquids extracted as the benzene-soluble fraction were analysed by 13C n.m.r. spectroscopy to obtain structural parameters, and were also subjected to elemental analysis to study the efficiency of heteroatom removal. Iron sulphide (FeS2) converted about 80 wt% of the coal into the benzene soluble fraction, but (NH4)2SO4 converted only 40 wt%. Surprisingly, the Fe2O3(SO4)2− in spite of the sulphate gave a similar coal conversion to FeS2. The coal liquids obtained using FeS2, (NH4)2SO4 and Fe2O3(SO4)2− catalysts consisted of aromatics with a short side chain and fewer heteroatoms, longer side chain and more heteroatoms, and longer side chain and fewer heteroatoms, respectively. It was concluded that a bifunctional catalyst, FeS2Fe2O3(SO4)2−, gives excellent results for coal liquefaction under the experimental conditions used.

Application of carbon-13 NMR spectroscopy for hydrogen-deuterium exchange between nuclear protons of phenol and deuterium or deuterium oxide over various metallic oxides

Carbon-13 NMR spectroscopy has been employed to study the H-D exchange reaction between phenol and deuterium gas or deuterium oxide in order to investigate the adsorptive structure of chemisorbed phenol and the surface properties of various oxides. The six metallic oxides selected for this study were acid catalysts (..gamma..-Al/sub 2/O/sub 3/ and SiO/sub 2/-Al/sub 2/O/sub 3/), base catalyst (MgO), and reducible catalysts (ZnO, Fe/sub 2/O/sub 3/, and ZnO-Fe/sub 2/O/sub 3/). Three types of deuteration of the carbon nuclei of phenol have been found: deuteration of the carbon nuclei at each position of phenol, at both the ortho and para positions, and at the ortho position only. Furthermore, it has been found that colored Fe/sub 2/O/sub 3/ shows an acidic nature as well as SiO/sub 2/-Al/sub 2/O/sub 3/ and ..gamma..-Al/sub 2/O/sub 3/, MgO shows basic nature as is well known, and ZnO shows a bifunctional nature (both acid and base). It is concluded that the deuteration of carbon nuclei is strongly influenced by the surface properties of the catalysts and the adsorptive structure of adsorbates.

Selective steam reforming of alkylated hydrocarbons and coal liquids over NiOFe2O3 catalysts

Abstract The major objective of the present work is to develop a new process for upgrading coal liquids by achieving the selective dealkylation of alkylated aromatics in coal liquids without hydrogen. A selective steam reforming process was investigated using NiO Fe2O3 catalysts at 480°C in a stream of nitrogen at atmospheric pressure. The catalysts used were of three kinds. Catalyst A was prepared by a conventional coprecipitation method of nitrates with ammonium solution, and had a molar ratio of Fe2O3 to NiO of 0.3:0.7. Catalyst B was prepared by impregnation of K2CO3 on catalyst A. The preferred amount of K2CO3 was found to be 0.3 wt.-% of catalyst A. Catalyst C was the catalyst supported on active carbon. The effective amount of the NiO Fe2O3 (0.7:0.3) phase was about 8 wt.-% on the active carbon. Selective steam reforming of toluene using the above catalysts was effected to determine optimum reaction conditions. Reaction temperature of 480°C and W/F of 42.8 gcat./h/mole feeds for catalysts A and B were found to give optimum results. However, W/F in the case of catalyst C was 30.1 g h/mole feed. In all cases, the partial pressure of nitrogen was 0.17 atm and the molar ratio of water-to-toluene was 5.1. Coal liquids as well as tetralin, indane and acenaphthene generally found in the coal liquids were individually tested under the same reaction conditions. Catalyst C showed highest activities and long catalyst life. Typically, 45% of toluene fed was converted to benzene and gaseous products such as hydrogen, carbon monoxide, carbon dioxide and methane. The selectivity for benzene was about 70% maximum. Indane in the coal liquids was selectively converted to alkylbenzenes such as benzene, toluene, ethylbenzene and xylenes, but tetralin and acenaphthene were dehydrogenated to naphthalene and acenaphthylene, respectively.

Role of water vapour in the carbon monoxide–water reaction system on an iron catalyst

Fourier transform i.r. techniques have been used to identify intermediates in the reaction if CO with water vapour over an iron catalyst.