Akimitsu Matsumura

Dual character of H2S as promoter and inhibitor for hydrodesulfurization of dibenzothiophene

Abstract Hydrodesulfurization (HDS) of dibenzothiophene (DBT) over laboratory synthesized bulk MoS2 catalysts using batch microautoclave reactor was studied. Influence of H2S (wide range level) on the DBT HDS activity and selectivity was investigated. In general, H2S was found to inhibit the direct desulfurization route that leads to biphenyl regardless the catalyst applied. However, the hydrogenation pathway which mainly produces phenylcyclohexane inferred to be either uninhibited or even more interestingly highly promoted by the presence of H2S depending on the catalyst nature. The ultimate sum impact of H2S on the catalytic activity shows two extremes, inhibition and promotion. Mechanism of H2S effect is proposed.

Methanol-mediated extraction process for the separation of phenolic compounds from coal liquids

Abstract Phenolic compounds in a naphtha distillate of coal liquid were efficiently extracted into water by using methanol as a mediator for the extraction. The effects of extraction solvents on extraction yields and selectivities of phenolic compounds were examined.

Methanol-mediated extraction for coal liquid (2) — the effect of phase separation caused by methanol on naphtha fraction derived from Wyoming coal

Abstract Methanol-mediated extraction, which the authors have developed, was conducted on the naphtha fraction derived from Wyoming coal. When 0.4–1.5 times methanol was added to the feed oil, the mixture formed a two-phase system. The extraction yield of phenol ranged from 86.3% to 99.2% and that of oil fraction ranged from 65.5% to 91.0%. This indicates that the extraction of phenol by methanol only was ineffective. Two extraction methods, extraction with water regardless of the presence of phase separation (method A), and that after separating the formed phase (method B), were conducted to compare the effect of phase separation on the extraction yield and selectivity of phenol. They had no significant differences between two extraction methods. From these results, we concluded that method A is applicable even if phase separation may occur by adding methanol.

Free radicals formed in hydrotreated coal liquid and influence of oxygen

The behavior of radicals formed in hydrotreated coal liquid with heat treatment and the influence of oxygen have been investigated by electron spin resonance (E.S.R.) spectroscopy. A set of E.S.R. spectral lines identified as phenalenyl radical appears from 50/sup 0/C as the oil is heated in argon atmosphere. The radical concentration is enhanced with temperature, reaches a maximum between 130 and 150/sup 0/C and then decreases at higher temperatures. The radical is very stable even at 200/sup 0/C for the sample hydrotreated under mild condition, whereas the radical in the sample treated under severe conditions disappears drastically from 150/sup 0/C. When oxygen is introduced in the oil, the radical is converted into semiquinone and/or aryloxy radicals and stable molecules. The treatment in the presence of oxygen at higher temperatures is considered to accompany the formation of other aryloxy radicals by the reaction of aromatic hydrocarbons and oxygen.

Oxidative Desulfurization of Naphtha with Hydrogen Peroxide in Presence of Acid Catalyst in Naphtha/Acetic Acid Biphasic System

Oxidative desulfurization of naphtha with H2O2 in the presence of H2SO4 in the naphtha/acetic acid (AcOH) biphasic system was investigated. All organosulfur compounds examined were smoothly oxidized in AcOH by peracetic acid effectively formed from AcOH and H2O2 in the presence of H2SO4. The order of the oxidation reactivities was sulfides, disulfides > benzothiophenes > thiophenes. The organosulfur compounds in octane were also oxidized with H2O2 in the presence of H2SO4 in the octane/AcOH biphasic system. The oxidation proceeded in the AcOH phase and most of the oxidized sulfur compounds resided in this phase, resulting in the successive removal of the sulfur compounds from the octane phase. This oxidative treatment effectively reduced the sulfur content of naphtha, and adsorption with silica gel further reduced the sulfur content to below 0.5 mass ppm. In addition, hydrodesulfurization is an effective pretreatment for this oxidative desulfurization of naphtha, resulting in further reduction of the sulfur content to below 0.1 mass ppm.

Particulate Emission Characteristics from a Middle-Duty Diesel Vehicle Fueled with GTL Gas Oil

A middle-duty diesel truck was driven by 7 kinds of test gas oil which contained a GTL (gas to liquid) gas oil (middle distillate of Fischer-Tropsch synthesis oil) with the Japanese 10-15 mode and a truck mode determined by Kawasaki City, and its exhaust emission was measured.Compared with emission characteristics by an ordinary commercial gas oil, the GTL gas oil caused negligible change in NOx emission, but showed 20% and more of the decrease in CO and HC emissions.Concerning PM emission, a large decrease as large as 56% was attained for both test modes. The introduction of the GTL gas oil into local areas severely polluted by diesel-derived PM was expected to have a considerable effect. Moreover, the content of aromatic hydrocarbons in the test gas oil had a high correla-tion with PM emission, and it was found that a decrease in aromatic hydrocarbons in the gas oil was effective for decreasing PM emission.For PAHs emission such as benzo (a) anthracene (B (a) A), 7, 12-dimethylbenzo (a) anthracene (DB (a) A), benzo (b) fluoanthene (B (b) F), benzo (k) fluoanthene (B (k) F), benzo (a) pyrene (B (a) P), indeno (1, 2, 3-cd) pyrene (IPyr) and benzo (ghi) perylene (B (ghi) P), 75% and more of the total amounts of the all PAH emission were reduced by using GTL gas oil for both test modes, compared with the commercial gas oil. Individually, B (a) A, DB (a) A, B (b) F and B (k) F showed especially a high positive correlation with the content of aromatic hydrocarbons in the test gas oil.

An attempt to separate nitrogen compounds

Abstract Coal liquids contain large amounts of nitrogen and oxygen compounds which make the processing of these into fuel uneconomical compared with petroleum. This paper investigates a method of separating the nitrogen compounds as sediments to provide valuable chemicals and clean fuel. Indole contained in coal liquids was photo-oxidized in carbon tetrachloride. The presence of galvinoxyl in the photo-oxidation process affected the formation of sediments in such a way as to suggest a radical reaction process. Whilst increased indole concentration led to increased sediment formation, the percentage yield was lower due to increased solubility of the sediment in highly polar solution. An optimum concentration is therefore indicated.

Hydrotreating of Shale Oils (Part 1)

コンドル産オイルシェールから得られたシェールオイルの灯軽油留分を, Ni-Mo-Al2O3系工業触媒により水素化処理を行い, 主として脱窒素精製について検討した。その結果, 反応温度の上昇, 水素圧力の増加, LHSVの減少に伴い, 脱窒素率およびH/Cは高くなり, 比重および粘度は小さくなった。脱窒素率は一次で整理され, その活性化エネルギーは, 水素圧力25, 50, 100kg/cm2でそれぞれ10.6, 17.4, 30.1kcal/molであった。また, シェールオイルの灯軽油留分の脱窒素反応は, 窒素含有量が石炭液化油などと比較して多いにもかかわらず容易であることを明らかにした。