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A time-series analysis of dominant reactions is proposed for kinetic interpretation of catalytic cracking of an olefin hydrocarbon with carbon number C8. The analysis considered four dominant reaction groups: cracking, skeletal isomerization, cyclization and hydrogen transfer. The kinetic parameters of normal, mono-, di-and tri-branched hydrocarbons as well as naphthenes were determined so as to follow the tendency of the experimental data. The analysis revealed that the reaction rate of isomer cracking was faster than that of linear hydrocarbon one, suggesting that the cracking product was produced dominantly via isomerization rather than direct cracking of linear hydrocarbons. These results implied that the conditions suitable for suppressing over-cracking and prevailing skeletal isomerization lie in the range of lower temperature.

In this study, a novel method for the production of biodiesel under mild conditions using fine particles of sodium methoxide formed in dimethyl carbonate (DMC) is proposed. Biodiesel is generally produced from vegetable oils by the transesterification of triglycerides with methanol. However, this reaction produces glycerol as a byproduct, and raw materials are not effectively utilized. Transesterification with DMC has recently been studied because glycerol is not formed in the process. Although solid-state sodium methoxide has been reported to be inactive for this reaction, the catalytic activity dramatically increased with the preparation of fine catalyst powders by crystallization. The transesterification of canola oil with DMC was studied using this catalyst for the preparation of biodiesel. A conversion greater than 96% was obtained at 65 °C for 2 h with a 3:1 M ratio of DMC and oil and 2.0 wt% catalyst.

Electromagnetic wave absorbing properties in GHz region were investigated for magnetite prepared by hydrogen reduction of hematite, which was synthesized via drip thermal oxidation using a fluidized bed. The magnetite powder product showed better absorption ability when the precursor hematite was prepared at a higher bed temperature, which also induced an improvement in morphology. This morphological enhancement is believed to result from the rapid thermal oxidation treatment of the hematite powder in the bed along with an accelerated evaporation of aqueous FeCl2 solution.

Amorphous Cu–Zr metallic alloys were studied as precursors to catalysts for methanol steam reforming to produce hydrogen. The alloy ribbons were prepared by single-roll rapid solidification, and the optimum pretreatment method and conditions were determined. The activity of the catalysts prepared by the improved pretreatment method was greater than that of previously prepared catalysts by two degrees of magnitude. The addition of a very small amount of Pt enhanced the activity without increasing CO formation.

Good fluidization was generally established when fine and light catalyst particles were fluidized. However, a large decrease in the fluidization quality was observed when two types of particles composed of different materials were mixed and fluidized, even though good fluidization was established with each type of particle alones. Formation of gas channeling was observed for binary mixtures of particles in a two-dimensional (2D) fluidized bed. In a three-dimensional (3D) bed, measurement of the pressure fluctuation showed that abnormal fluidization occurred due to mixing of the particles. In addition, measurements of the minimum fluidization velocity and emulsion phase expansion indicated that particle agglomeration occurred. The phenomena observed in the fluidized bed with the mixture of particles are quite similar to those observed for Group C particles. On the basis of the direction of the electrostatic charge, the particles were separated using electrodes installed above the fluidized bed surface. It was confirmed that one type of particle was positively charged and the other was negatively charged. Thus, it was concluded from these results that the bipolar charging caused by the difference in chemical composition of the particles induced the agglomeration phenomena and poor fluidization.

Transient defluidization occurs when fluidizing gas is switched from a lower density gas to a higher density gas. The intensity of this phenomenon increases with decreasing particle size and with increasing difference between gas densities. In order to investigate the mechanism of this effect, images of the transient phenomenon were captured using a video camera and visualized using digital image conversion. Gray-scale pictures were obtained based on the transmittance of back light through the emulsion phase in a thin two-dimensional fluidized bed. The gray-scale pictures were transferred into pictures with a color gradation. The generation, expansion, and elimination of defluidization after switching of the fluidizing gas can clearly be seen by observing the reconstructed color movies.

A gas recycling method for establishing stable operations of a fluidized catalyst bed is studied in order to perform reactions accompanied by a decrease in the number of moles. Two operation modes using gas recycling are evaluated to prevent defluidization and establish stable operation. For the first operation mode, because the influence of the decrease in the number of moles on the fluidization quality is reduced by adding a dilute gas to the feed, the reactor is operated with high conversion and a part of the outlet gas is recycled to the reactor inlet. The fluidization quality is also improved by decreasing the reaction rate. Therefore, for the second mode, the reactor is operated with low conversion, and the unreacted components in the outlet gas are separated from the product gas and recycled to the reactor inlet. It is possible to increase the overall conversion to a high level by gas recycling. Experimental data in previous studies and a fluidized-bed-reactor model that considers the decrease in the number of moles are used in order to determine the required recycle ratio and reaction rate constant for establishing a stable operation. Even when a reaction is accompanied by a 50% decrease in the number of moles, the required recycle ratio is below 9 for the recycle mode without separation and below 5.5 for the recycle mode with separation.

Hydroxyapatite (HAp) powder was produced by drip pyrolysis in a fluidized bed (DPFB) at 913–1113 K with dry air. In this study, HAp powders derived using different concentrations of a solution-type precursor material were compared with those derived using slurry-type precursor materials. From a solution-type precursor containing calcium nitrate and ammonium phosphate dibasic, fine HAp powders with mean particle sizes of approximately 8–40 μm were produced, depending on the solution concentration and reaction temperature. In these cases, bimodal particle size distribution was observed. Spherical alumina of 250 μm was found to be superior to silica sand of 270 μm as the coarse medium particles in reducing contamination of the product powder. The thermal stability of HAp derived from a slurry-type precursor after 1-day aging was improved by DPFB. HAp powders derived from the solution-type precursor material were Ca-deficient, and their Ca/P molar ratio increased with bed temperature. In contrast, the Ca/P molar ratio of HAp powders from the slurry-type precursor material was nearly stoichiometric. Morphology strongly depended on the starting precursor material. The solid collection ratio was closely related to the population of product particle sizes larger than 25 μm.

In industrial fluidized bed processes, the system often involved a change in volumetric flow. Defluidization occurs when reactions involving a decrease in gas volume are carried out in a fluidized catalyst bed. This is due to decrease in gas velocity below the minimum fluidization velocity in the emulsion phase. One method to improve fluidization quality is to supply an inert gas with reactant gases: similar effect can be obtained by supplying an excessive amount of one of the reactants. In the present study, the effect of a diluted reactant gas on fluidization quality is quantitatively analyzed by performing CO2 hydrogenation in a fluidized catalyst bed. Stable operation can be established by operating the fluidized bed to avoid the conditions contained in the defluidization zone using two parameters that influence fluidization quality.

For the biodiesel-fuel production by methanolysis, the reaction mixture is composed of a methyl-ester phase and a glycerol phase. One of the reactants, triglyceride, is mainly contained in the ester phase. The other reactant, methanol, is easily dissolved in the glycerol phase. Therefore, the methanol in the system is not effectively used for the reaction due to interface mass transfer resistance. An excess amount of methanol is required to increase the conversion in single-step operation. Since the glycerol phase is removed during the operation, a two-step batch operation can effectively intensify the process. In the present study, the optimal operating conditions to increase the conversion are obtained for the methanolysis of rapeseed oil using a KOH catalyst. The distribution ratio of methanol addition in the first step was about 0.8, which is confirmed by a simple reaction model.

There are many industrially useful reactions accompanied by the change of the gas volume due to the stoichiometry. Although it is important to consider the effects of the gas-volume changes for the accurate estimation of the reactor performance, the effects on the fluidization properties have not been experimentally studied. In this study, experimental simulation was carried out to study the effects of the increase in gas volume on the fluidization properties. The gas volume was increased by the evaporation of water impregnated in the pores of alumina particles at elevated temperature. The effects on the expansion of the emulsion phase, average bubble holdup, bubble size and pressure fluctuations were studied. The bubble growth, splitting and coalescence would become vigorous, whereas the emulsion phase expansion was not affected and the bubble size was slightly increased.

Defluidization and a decline in fluidization quality were observed in reactions involving a decrease in gas volume. This was due to a reduction in gas velocity in the emulsion phase owing to the reactions. The decrease in the gas velocity led to a reduction in the emulsion phase voidage. Finally, a part of the fluidized bed was defluidized and lifted up through the column like a moving piston. In the present study, methanation of carbon dioxide was carried out as a model reaction, and the effect of the two-stage distribution of the fluidizing gas on the improvement of the fluidization quality was investigated. The bed was fluidized by supplying hydrogen from the bottom of the fluidized bed. The other reactant, carbon dioxide, was supplied from the bottom distributor and a secondary gas inlet. By using this method, it was possible to avoid defluidization. The influences of the level of the secondary inlet and the distribution ratio of carbon dioxide on fluidization quality were studied by plotting two parameters that affect fluidization quality.

The interface area between the bubble and emulsion phases in a fluidized catalyst bed is one of the important parameters used to analyze and design the fluidized bed reactor. We used a fast-scanning X-ray CT system to observe the bubble shape and structure. We then obtained the transient 2-dimensional cross sectional gas-phase distribution in a fluidized catalyst bed. Using image-processing techniques, pseudo 3-dimensional images of the bubbles were reconstructed. The bubble structure was studied based on the 3-dimensional images and the previously obtained results in a 2-dimensional fluidized bed. It was found that the bubble shape was not spherical but complicated, and that the bubbles ascending in a fluidized catalyst bed consisted of some smaller bubbles.

A room-cooling system of 2 kW capacity fueled by wood pellets was designed, built and tested. The system was demonstrated during summer at the Yakushima Field Station of Kagoshima University, Japan. It contained a pellet feeder, a pellet burner, a heat exchanger, a lithium bromide–water absorption heat pump and a control unit. The volume of the test room was 36.9 m3 and ambient temperature 30 °C. The airflow temperature from the room unit was decreased to 16 °C by the system, and the room temperature could be successfully controlled to 24 °C steady state. Room heating in winter was also demonstrated. Since the air was heat exchanged, the overall energy efficiency of the cooling system was low at about 19%. However, the calculation based on the heat flow showed that the efficiency could be enhanced to about 75% by direct heating of the regenerator by the flue gas.

The oligomerization of light olefi ns, such as ethylene, propylene, 1-butene and isobutene, catalyzed by methane- sulphonic acid (MSA) was evaluated to synthesize liquid hydrocarbons in a high pressure continuous fl ow reactor for 250 min at 20 to 40�C. The liquid hydrocarbons separated from the MSA catalyst were analyzed by combined gas chromatography with mass spectrometry. The hydrocarbons were classifi ed by molecular weight as gasoline, kerosene and light oil. Although ethylene and propylene were slightly dissolved into the MSA, no further liquid product was obtained after the reaction period. The yield of liquid product from isobutene was larger than that from 1-butene. The selectivity for gasoline was lower than that for kerosene or light oil. The recovered MSA was replaced 10 times into the reactor to elucidate the effect of recycling on catalyst deactivation. The activity of recycled MSA was the same as the fresh catalyst. On the other hand, the reaction mixture catalyzed by sulfuric acid was not separated into the hydrocarbon layer and catalyst layer after recycling 3 times. Oligomerization of 1-butene with a small amount of water to clarify the effect of impurity showed that the catalytic activity of MSA sharply decreased with water content. Methanesulphonic acid is an effective catalyst for the selective synthesis of gas oil from butenes.

The vapor phase Beckmann rearrangement of cyclohexanone oxime (CHO) was carried out over TS-1 with an MFI pore structure and SSZ-31 and SSZ-24 with pore sizes larger than that of MFI to elucidate the effect of the pore size on catalyst deactivation. The deactivation constant over SSZ-24 was the highest among the zeolites used in the study. Furthermore, when the ratio between the molecular size of e-caprolactam (CL) and the pore size of zeolite was unity, the deactivation constant was maximum over the zeolites at similar acidity. These results indicate that since CL produced on the active sites cannot diffuse from the micropores, the CL reacts to form coke or its precursor over a long residence time. The pore size of the zeolite is the main controlling factor of catalyst deactivation during the Beckmann rearrangement.

ポリオレフィン（PP・PE等）樹脂の酸化防止効果を向上させる目的で，ビタミンE骨格をもつ2種類の化合物，S-13およびS-19を合成した。これをPPに対して0.005 wt％添加して，酸化防止効果をメルトインデックス（MI）およびイエローインデックス（YI）を用いて評価した。その結果，これらの酸化防止剤は単独でも効果があるが，既存のフェノール系およびリン系酸化防止剤と組み合わせることで相乗的な効果が得られることが分かった。過去の酸化防止作用についての知見等から，今回合成した酸化防止剤のラジカルとの反応速度が非常に大きいため，PPやPE内で生成した炭化水素ラジカルあるいはそのパーオキシラジカルと優先的に反応し，その後リン系あるいはフェノール系酸化防止剤により再生されることが，この相乗効果の原因であると考えられた。

Methanol steam reforming was carried out over catalysts prepared from glassy Cu-Zr alloys containing a small amount of noble metals. The reforming activity increased when the alloys were treated at a temperature above the crystallization point, whereas the as-cast alloy did not have the same activity. The reforming activity of the heat treated alloys increased with the decreasing content of noble metals down to 1 at%. The DSC (differential scanning calorimetry) of the original alloys revealed that the activity was related to the range of the temperature interval between glass transition and crystallization as well as the heat of glass transition. The glassy Cu-Zr alloys with small amount of noble metals changed to fine copper particles supported on zirconium oxide by the heat treatment. The copper particle size of the treated alloys was related to the endothermic heat. These results indicated that the noble atoms were uniformly dispersed into the glassy Cu-Zr alloys at the glass transition temperature. Highly active reforming catalyst can be prepared from an glassy Cu-Zr alloys containing a small amount of noble metals.

The vapor–solid phase Beckmann rearrangement over HZSM-5 zeolite and silica-alumina was carried out to elucidate the effects of reaction temperature and diluent solvent on the selectivity to e-caprolactam (CL) and the catalyst deactivation. When the HZSM-5 was regenerated with oxygen atmosphere after the rearrangement using methanol as the solvent, the cyclohexanone oxime (CHO) conversion decreased with the regeneration number, whereas the caprolactam selectivity was almost constant. The catalyst deactivation at the fresh zeolite was largest among the regenerated zeolites. Although the crystalline structure did not change with the regeneration, the acid strength of the zeolite decreased with the regeneration number. These results suggest that the acid sites in the extra-lattice of the zeolite were responsible for the catalyst deactivation. It was found that the yield of the oligomers of e-caprolactam, such as dimers, trimers and tetramers, changed with the catalyst deactivation constant. The rearrangement was carried out over silica alumina to obtain a significant amount of oligomers. As a result, the catalyst deactivation was related to the selectivity of the tetramer. The tetramer yield significantly changed with the solvent. These results indicate that the oligomer as a coke precursor was easily removed by vapor of a polar solvent, such as alcohol or acetonitrile.

Fluidized catalyst beds have been used in chemical and refinery processes and studied extensively for more than 50 years. However, the features of this reactor are still not understood perfectly. There is still much more to learn about the fluidized catalyst beds. It is important to elucidate the bubble behavior and the contact between catalyst particles and reactant components in the reactors. Understanding the features of the reactors contributes to the proper catalyst design together with the appropriate design and operation of the reactors. In this paper, the influence of gas properties on the bubble behavior is described, and pseudo-3-dimensional images of bubbles are shown. The important effects of direct and successive contact in the bed are discussed regarding conversion and selectivity. The reaction analysis showed that the selectivity could be improved by the effective use of the direct contact catalyst particles. The synergy effect of the three factors, i.e., catalyst activity, contacting featu...

A study was carried out to see if the potential of renewable energy sources other than hy droelectric power, such as wind, photovoltaic, solar thermal, biomass and waste energy sources, can meet the current energy consumption in Yakushima. The current electricity consumption can be covered by wind and photovoltaic energy sources. The total potential of wind and photovoltaic energy sources is 5.4 times as much as the current electricity consumption. LP gas and kerosene can be replaced by solar thermal and biogas energy. The potential of plant biomass and municipal waste is not sufficient (approximately one third) to cover the rest of the fossil fuels (gasoline, diesel oil and heavy oil). Also, plant biomass and municipal waste must be converted into fluid form. This shortage can be covered by the po tential of wind and photovoltaic energy sources. We also investigated the possibility of tourism expansion using the potential of wind and photovoltaic energy sources. Taking into account three types of capacity (energy, accommodation and transportation), Yakushima can accept approximately four times as many tourists as the current number of tourists.

High-silica ZSM-5 zeolites were synthesized by the addition of pentavalent ions, such as phosphorus and arsenic ions, to the mother gel for the zeolite preparation. The Beckmann rearrangement of cyclohexanone oxime in the vapor phase was carried out over the high-silica ZSM-5 zeolites or zeolites modified with noble metals to elucidate the effects of the diluent gas and diluent solvent on the e-caprolactam selectivity and catalyst deactivation. The catalyst lives of the zeolites modified with noble metals were much longer than that of the unmodified zeolite during the rearrangement using carbon dioxide and methanol as the diluent gas and diluent solvent, respectively. Furthermore, the life of the zeolites modified with noble metals was significantly improved by using a small amount of oxygen as the diluent gas. In this case, methanol was the most suitable diluent solvent for the improvement of catalyst life. The catalyst life decreased with increased cyclohexanone oxime concentration in methanol. Therefore, the coke or coke precursor on the acid sites was presumably removed by methanol vapor. These results indicate that a prolonged catalyst life in the vapor phase Beckmann rearrangement can be achieved by the optimum combination of catalyst and reaction atmosphere.

反応によってガス体積(モル数)が減少する反応を流動触媒層で行った場合の流動化状態を調べるために, ガラス製の反応器を使用して層内で起きる現象を観察した. その結果, 反応が進行すると, 条件によっては層上部の触媒粒子が凝集し, 流動化が停止して, 塔径大の粒子層の塊が流動化ガスによって持ち上げられることがわかった. このようにエマルション相が凝集することの原因の一つとして, エマルション相と気泡相のガス密度の違いが考えられるため, この影響について調べた. その結果, 本反応においては, ガスの密度差は原因とならないことがわかった. モル数減少反応が起きている場合の流動性の低下はエマルション相における反応にともなうガス体積の減少によって, 層が収縮し, 気泡の上昇が妨げられることが大きな原因と考えられる.

The effect of asphaltene (ASP) decomposition on catalyst deactivation under deep desulfurization conditions was investigated by reduction of sulfur from 0.3 to 0.1 mass% in a treated atmospheric residue (AR) over two kinds of commercial catalysts, namely CDS-R2 and 46Y-678, in a pilot scale fixed bed reactor. The CDS-R2 catalyst was supported on γ -alumina with medium pore size (11 nm) and the 46Y-678 catalyst was supported on Y-type zeolite. The life of 46Y-678 was longer than that of CDS-R2, but was not adequate for application to commercially operated hydrotreating equipment. The rapid decomposition of ASP on the catalyst may be responsible for the catalyst deactivation from analysis of ASP in the product oil. Characterization of the used catalyst and the asphaltene revealed that coke was uniformly deposited on the catalyst and the coke content after 1000 h of time on stream was almost the same as that after 1 year in a commercial hydrotreating process. The coke content increased at the outer surface of catalyst by growth of a carbon shell. Decomposition of asphaltene is probably responsible for rapid catalyst deactivation in deep hydrodesulfurization.

Hydrodesulfurization (HDS) of atmospheric residue (AR) carried out over Ni_Mo or Co_Mo catalyst requires a sudden increase in the reaction temperature for the desired desulfurization at the end of operation (EOR). This phenomenon is mainly caused by reduced diffusion rate due to metal deposition in the pore mouth. The present study performed HDS over catalysts with different pore size to separately examine the effects of metal and coke deposition on catalyst deactivation. HDS catalysts used in a commercial process for 1 year were analyzed by EPMA to determine the coke and metal distribution along the catalyst radius. A model equation was developed to quantitatively estimate the coke and metal distribution. The model equation could estimate parameters such as Thiele modulus and catalyst properties coefficient. Furthermore, the equation was applicable to used catalyst obtained from commercial equipment and to used catalysts with different pore radii after HDS of Boscan crude containing large amounts of metals and asphaltenes. The distributions of coke and metals could be simulated with the model equation, giving 0.01 and 4 for the Thiele moduli for coke and metal, respectively. The model equation developed in this study is useful to estimate the service life of HDS catalyst.

Hydrodesulfurization (HDS) of atmospheric residue (AR) over Ni-Co-Mo catalysts supported on y-alumina was carried out to examine the effect of alumina pore size on HDS activity, hydrodemetallization (HDM) activity and initial catalyst deactivation under deep hydrodesulfurization conditions. HDM activity slightly increased with alumina pore size, but HDS activity decreased due to the decrease in the surface area of the support. Deactivation of the HDS catalyst was greater on large pore size supports than on medium pore size supports. The combination of HDS catalyst with large pore size supports (40%) and medium pore size supports (60%) did not improve the catalyst life. HDS was carried out with the large pore size support catalyst at the upstream side in the first reactor and the medium pore size support catalyst at the upstream side in another reactor. Catalyst deactivation was greater in the former than in the latter reactor. These results suggest that HDS catalyst supported on alumina with medium pore size has a higher performance than HDS catalyst supported on alumina with large pore size for deep HDS. To examine the behavior of asphaltene (ASP) at the reaction temperature, adsorption of ASP was investigated on catalyst supports with different pore size. ASP was a large molecule at low temperatures, but the molecular size decreased at HDS reaction temperature caused by the dissociation of the molecular structure. Furthermore, ASP containing sulfur was preferentially adsorbed on the catalyst support. The chemical interaction between ASP and alumina indicates that alumina is a good support for the HDS reaction., 常圧残油の水素化脱硫反応（HDS）を細孔径の異なるγ-アルミナに担持したニッケル-コバルト-モリブデン触媒を用いて，深度脱硫条件で常圧残油の反応を行い，水素化脱硫（HDS）活性，水素化脱メタル（HDM）活性および触媒活性劣化に及ぼす細孔径の影響を検討した。HDM活性は細孔径とともにわずかに増加したが，HDS活性は細孔径とともに減少した。また，大きな細孔径をもつ担体に担持した触媒の初期活性劣化は，中位の細孔径をもつ触媒よりも大きくなった。大きな細孔径をもつHDS触媒（40％）と中位の細孔径をもつHDS触媒（60％）の組合せ，あるいは二つの触媒の充填順序を変えて反応を行ったが，組合せによる触媒寿命の延長効果は小さく，特に大きな細孔をもつ触媒を上流側に配置すると触媒寿命は短くなった。アスファルテン（ASP）を多く含む重質な深度脱硫操作に対しては，中位の細孔径をもつ触媒がすぐれた性能を発揮することが分かった。これらの結果を説明する目的で，反応温度付近におけるASPの触媒担体への吸着実験を行った。ASPの吸着量は，低温では細孔径とともに増加したが，温度の上昇に従い，細孔径による吸着量の差が小さくなった。すなわち，ASP分子は高温になると，ミセルの状態を解いて比較的小さな分子になった。さらに，硫黄を含むASPは触媒担体に吸着しやすい性質をもつことが分かった。このような化学的相互作用により，アルミナはHDS触媒の担体として高性能を示すと考えられる。

A new method has been used to visualize particle movement and to observe the emulsion flow in a two-dimensional fluidized bed. The method is based on the ultraviolet light activation of particles impregnated with a photochromic dye solution. When activated, the particles changed their color to dark blue allowing their movement to be easily distinguished and tracked. This method enabled us to observe continuously the movement of bubbles and fine particles around a bubble in a fluidized catalyst bed. A detailed study of the particle movements around the bubbles showed that even when the bubble ascending velocity is large, the bubble is not accompanied by an upward emulsion flow. Author Keywords: Fluidization; Fluidized bed; Visualization; Photochromic dye; Particle movement

高速X線CTスキャナを利用して触媒流動層の分散器より0.6mの高さにおいて気泡の断層画像を得た．流動層には内径46mm，高さ1.5mのアクリル樹脂製のカラムを使用した．空気を流動化ガスとし，空塔ガス速度0.01–0.07ms− 1の範囲で測定を行った．得られた断層画像を使用して気泡の境界部の解析を行った．エマルション相の空隙率が気泡界面付近でどのように変化するか調べた．また，気泡形状を考慮した界面積を求め，気泡長さから球状を仮定して求められる気泡の界面積との比較を行った．その結果，気泡形状を考慮した界面積は気泡を球状と仮定して推算される界面積よりもかなり大きくなることがわかった．

This article describes a pilot plant test, which was carried out to examine the effect of start-up operation conditions on catalytic performance in the commercial hydrotreating equipment. From the simulated several pilot tests, it was found that the operation conditions of this commercial equipment were very severe and the hydrogen supply to the catalyst active site was critical. When the heavy residue containing large amount of asphaltene was supplied at the start of run (SOR) in the commercial equipment, the permanent adsorption of carbonaceous deposit on the active site should cause leading the catalyst deactivation.

高脂肪族•低硫黄常圧残さ油 (残さ油A) をアルミナに担持した脱硫触媒を用いて水素化改質を行うと, 触媒の活性劣化速度が低脂肪族•高硫黄残さ油 (残さ油B) のそれよりも大きくなった。残さ油の脂肪族部分の分解反応は, 脱メタルおよび脱硫触媒の担体のアルミナ上で進行し, 生成したオレフィンによるコーク生成が活性劣化の原因になることが分かった。アルミナよりも強酸性を示すシリカアルミナを担体とした触媒を用いると, 反応開始後1500時間程度において要求される性能を示す温度 (WAT) を20°C程度低下できるが, その後の触媒活性劣化は大きくなった。残さ油Aに40vol%の残さ油Bを混合して水素化処理を行うと, アルミナを担体とする触媒の活性劣化が抑制された。残さ油に含まれる硫黄が水素化改質反応のコーク生成を抑制するのに重要な役割を演じているが, 現在の触媒の組合せでは, 長い脂肪族炭素鎖をもつ残さ油Aを効率的に処理することはできなかった。