Minoru Kurita

The reactivities and the stabilities of the paramagnetic species formed on the surface of Al2O3MoO3CoO and SiO2MoO3CoO: The carrier effects of Al2O3 and SiO2☆

Abstract The rates of formation and decay, the concentration and the stability of the paramagnetic species on the surface of the catalysts (carrier-MoO3, carrier-MoO3-CoO) prepared from two oxide carriers, γ-alumina and silica gel, having identical surface areas and pore radius distributions, were studied by electron spin resonance (e.s.r.) using a mixture in which an aromatic hydrocarbon was added to the oxide with or without a solvent (benzene). The measurements were made either at 20 °C or at 20 · 300 °C. The cobalt ions did not interfere with the Mo6+ ions on γ-alumina, but reduced the activity of the Mo6+ ions on silica gel. R+, a hydrocarbon cation, was formed only when Mo6+ was present, while R+O★2− a complex ion which is different from R+, can be formed in the absence of Mo6+, though its amount was increased by Mo6+. R+ appeared only in the presence of solvent molecules while R+O★2− appeared without a solvent. The stabilities of R+O★2− and Mo5+ at 300 °C were far larger on γ-alumina than on silica gel. The effects of the carriers on the activities of the hydrodesulphurisation catalysts are in accord with the catalytic reaction scheme already reported.

Effect of the Dust Components on the Life of Catalysts Used for the Reduction of NOx in the Sintering Furnace Gas

Fe2O3-Al2O3およびV2O5-Al2O32触媒を用い,アンモニア接触還元法を焼結炉排ガス脱硝に適用した場合の問題,主としてダスト成分中触媒に付着しNOx還元能を低下させる成分の検討を行なった。焼結炉排ガス脱硝試験は,鉄鉱石焼結炉煙道の途中から排ガスの一部を吸引し,1000Nm2/hr移動層反応器によって行なった。排ガス処理に用いた触媒は100時間ごとに反応器から一部抜き出し,実験室で模擬ガスによる活性試験,触媒劣化要因を検討するための付着ダスト成分,表面積および細孔容穣などの分析,物姓測定を行なった。その結果,活性は経時的に低下するが,排ガス中のSOxによる影響は少なく,アルカリ成分とくにカリウム塩の付着量の増加と触媒の活性低下がよい対応を示すこと,Si,Ca成分など微細ダスト成分による触媒細孔の閉塞が認められることから,活性低下は,主としてダスト成分の付着に起因することが明らかになった。また,Fe2O3系触媒とV2O5系触媒で活性低下速度が大きく異なる原因として,K成分はFe成分が存在する場合容易に触媒に付着し,両者は複塩を形成すること,V2O5系触媒では触媒毒成分であるK成分の蓄積が主として触媒粒表面から数10μ程度にかぎられるのに対し,Fe2O3系触媒ではK成分は触媒粒内(150μ以上)まで侵入していることなどを明らかにした。

Fischer-Tropsch Synthesis with Tubular Reactor of 18.1 1. Catalyst Bed. II. Reactor with Temperature Gradient along Out-side Wall

The present experiments on the Fischer-Tropsch synthesis have been made with the reactor which was placed in a bath of oil boiling under a reduced nitrogen pressure. The heat transfer efficiency referred to the out-side wall of the reactor has been improved considerably, and, as a consequence, the magnitude of the bed over-temperature remains comparatively small, in spite of the high yield of the product attaining 24∼26 kg./day. The axial and the radial temperature profiles have been separately calculated on the basis of the concentration gradient determined along the heights of the reactor: first the calculation of the former profile under the assumption of uniform temperature across the bed, and secondly that of the latter profile at a cross section in the neighborhood of which the axial temperature is approximately constant. By the convenient choice of 600 kcal./m2 hr. °C for the tube wall coefficient of heat transfer referred to the out-side wall of the present reactor, the calculated axial temperatur...

Fischer--Tropsch synthesis in a tubular reactor with an 18. 1 liter catalyst bed. II. Reactor with temperature gradient along the outside wall. [Radial temperature profile calculated at cross section at which axial temperature was constant; no experimental evidence available for radial profile]

The present experiments on the Fischer-Tropsch synthesis have been made with the reactor which was placed in a bath of oil boiling under a reduced nitrogen pressure. The heat transfer efficiency referred to the out-side wall of the reactor has been improved considerably, and, as a consequence, the magnitude of the bed over-temperature remains comparatively small, in spite of the high yield of the product attaining 24∼26 kg./day. The axial and the radial temperature profiles have been separately calculated on the basis of the concentration gradient determined along the heights of the reactor: first the calculation of the former profile under the assumption of uniform temperature across the bed, and secondly that of the latter profile at a cross section in the neighborhood of which the axial temperature is approximately constant. By the convenient choice of 600 kcal./m2 hr. °C for the tube wall coefficient of heat transfer referred to the out-side wall of the present reactor, the calculated axial temperatur...

Fischer--Tropsch synthesis in a tubular reactor with an 18. 1 liter catalyst bed. I. Reactor with a constant temperature wall. [Catalyst of Fe/sub 3/O/sub 4/ 93. 25, Al/sub 2/O/sub 3/ 3, CaO 1, MgO 1, WO/sub 3/ 1, CuCl 0. 25, and K/sub 2/O 0. 5 part by wt]

By the aid of the calculating procedure developed by us on the basis of experimental data available in the synthesis with the reactor of 21. catalyst bed, prediction of the temperature profile as regards the synthesis with the reactor of 18.1 1. catalyst bed has been made. The predicted temperature profile expresses the tendencies observed in the actual synthesis with the latter reactor, though a complete agreement has not yet been obtained because of a lower output than was expected. The calculating procedure has been applied to draw the temperature profile on the basis of the present experimental concentration gradients along the reactor. The profile thus drawn agrees well with the measured one.

Fischer-Tropsch Synthesis with Tubular Reactor of 18.1 1. Catalyst Bed. I. Reactor with Constant Temperature Wall

By the aid of the calculating procedure developed by us on the basis of experimental data available in the synthesis with the reactor of 21. catalyst bed, prediction of the temperature profile as regards the synthesis with the reactor of 18.1 1. catalyst bed has been made. The predicted temperature profile expresses the tendencies observed in the actual synthesis with the latter reactor, though a complete agreement has not yet been obtained because of a lower output than was expected. The calculating procedure has been applied to draw the temperature profile on the basis of the present experimental concentration gradients along the reactor. The profile thus drawn agrees well with the measured one.

Concentration and Temperature Gradients along Packed Bed of 2l Iron Catalyst in Reactor for Fischer-Tropsch Synthesis

Fischer-Tropsch合成では多量の反応熱を発生し反応生成物が複雑である一方,,反反応応にに適適当当なな温温度度範範囲囲がが狭狭いいののでで,,、この反応装置の設計には多くの困難な問題が含まれる。ここにこの反応に伴なう物質の変化と熱の移動に関する知見を得るため,触媒2lを用いる反応管で3種の触媒につき,圧力,温度,空間速度,ガス組成などの異なる種々の反応条件にて合成試験を行ない, 反応管壁の異なった高さに設けた試料口より試料を抜き出して反応の進行状態を実測し, 触媒層の温度勾配を測定した。触媒層内の反応進行度から計算した反応熱分布は,既往の層内発熱量分布を仮定する伝熱の研究で用いられたいずれとも異なるので, ここでは実測の濃度勾配に基く反応熱分布の近似式をつくり, これを伝熱式に代入して解くことにより触媒層内軸および半径方向の温度勾配を計算した。その結果,軸方向の計算値と実測値とは比較的よい一致を示し,この計算方法で層内発熱量分布が知れている場合には触媒層の温度の検討ができることを知った。