炭化水素の気相接触酸化
スポンサーリンク
概要
- 論文の詳細を見る
The background and main points of recent works on vapor phase oxidation of C<SUB>3</SUB>, C<SUB>4</SUB> olefins and ethylbenzene with multi-component oxide catalysts are described.<BR>Fe-As and Mo-Ce (or Al, Ba, Sr) -As oxides were found to have high catalytic activity for producing acrolein by vapor phase oxidation of propylene with air. The activity of Fe-As oxide decreased with reaction time because of the escape of As component, especially in the reaction at high temperature, such as oxidation of i-butylene to methacrolein.<BR>This defect was eliminated and initial activity was kept by adding Li component to Fe-As system. With Fe-Li-As oxide of atomic ratio= 1 : 2 : 2.5 1 : 3 : 3, high yield of methacrolein was obtained from <I>i</I>-butylene at the temperature of 470°C.<BR>By means of searching direct oxidation of the olefins with Fe-As<SUP>5+</SUP> oxide systems and formation of As<SUP>5+</SUP> in As<SUP>3+</SUP> oxide systems and studying the structure of catalyst, following conclusions were obtained.<BR>The catalytic oxidation of α-CH bond to aldehyde is carried out by a cycle consisting of two reactions : <BR>2 As<SUP>5+</SUP> oxide + CH<SUB>2</SUB> = CR-CH<SUB>3</SUB> → 2 As<SUP>3+</SUP>oxide CH<SUB>2</SUB>= CR-CHO and<BR>2 As<SUP> 3+</SUP>oxide + O<SUB>2</SUB> → 2 As<SUP>5+</SUP>oxide (R : H or -CH<SUB> 3</SUB>).<BR>The former reaction, remarkably promoted by the Fe component in the catalyst, is always accompanied with formation of CO<SUB>2</SUB>, but proceeds more dominantly when As<SUP>5+</SUP> concentration is high. Two structures of -Fe-O-As- and -Li -O-As- were observed in Fe-Li-As oxide catalyst; the former is more easily reduced with olefin than the latter.<BR>-Fe-O-As- structure has at least two kinds of active site. Unsaturated aldehyde forms on one site and CO<SUB>2</SUB> on another site. Li-O-As structure is stable and instrumental in preventing the escape of As component into vapor phase.<BR>The activity of Mo-X-As (X : alkaline earth metal) oxide catalyst for oxidative dehydrogenation of 1-butene was studied in connection of its preparation and physical property.<BR>A Si-Ce-Sb oxide catalyst of new type showed relatively high activity for styrene formation by oxidative dehydrogenation of ethylbenzene.
- 社団法人 有機合成化学協会の論文