Direct Synthesis of Methyl Isobutyl Ketone from Acetone and Hydrogen with Metal Modified Solid Base Catalyst

• Main Authors: Lin, Kai shun, 林凱勛
• Other Authors: Liang,Bih-Fong
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/99940384525544236164

碩士 === 東海大學 === 應用化學系 === 84 === Abstract one-step synthesis of methyl isobutyl ketone (MIBK) from acetone and hydrogen over metal modified solid base catalysts has been studied at atmospheric pressure and 175~250℃by using a fixed-bed , integral-flow reactor . Two types of catalysts have been used : (1) metal oxides modified with sodium and palladium (Pd/Na/MgO , Pd/Na/NaOH/γ- Al2O3) ; (2) zeolites modified with palladium (Pd/KZSM-5 , Pd/Kβ) . The catalyst properties , i.e., the composition , the basicity , the surface area and the structure are characterized by the methods of atomic absorption , temperature- programmed desorption , surface adsorption and scanning electron microscopy . Sodium vapor deposition on magnesia followed by impregnation with tetraamine palladium(Π) chloride apparently enhances the catalyst basicity as compared with that of magnesia supported palladium ; Pd/0.47wt.-%Na/MgO exhibits the largest base amount . For catalysts of different supports , the base amount decreases in the order of Pd/Na/MgO > Pd/Na/NaOH/γ-Al2O3 > Pd/KZSM-5 > Pd/Kβ , in accordance with the catalyst activities . As the amount of palladium in Pd/Na/MgO increases , both acetone conversion and MIBK selectivity also increase but then decrease . Better acetone conversion and MIBK selectivity are obtained at higher pretreating temperature of hydrogen . The catalyst activity of Pd/Na/MgO increases with the reaction temperature but the decay rate also increases . The acetone/hydrogen molar ratio of 1 gives the highest acetone conversion . Increasing contact time causes an increase in the selectivity of diisobutyl ketone due to further reaction of MIBK with acetone and hydrogen . Based on the above results , the optimum reaction conditions are 0.5wt.-%Pd/0.47wt.-%Na/MgO , reaction temperature 200℃ , acetone /hydrogen molar ratio 1, W/FA 6g.h/mol and the pretreatment temperature of hydrogen 400℃ . According to the FT-IR results of acetone adsorption on Pd/Na/MgO , the following reaction mechanism is proposed : self condensation of acetone on catalyst base sites followed by dehydration on acid sites and then hydrogenation to yield MIBK .