|
The C4 mixture containing butadiene and maleic anhydride ( MA ) as raw material batch and continuous processes synthesis of 1,2,3,6 - tetrahydro phthalic anhydride (Δ4-THPA) and Δ4-THPA P 2 O 5 catalyzed heterogeneous preparation of liquid tetrahydro phthalic anhydride process were studied . 1, using the continuous synthesis of tetrahydro phthalic anhydride , examine the solvent , reaction temperature, pressure , molar ratio and duration affect and determine the optimum conditions for the the MA conversion rate and yield of Δ4-THPA . In tetrahydrofuran as a solvent , 10% of the concentration of maleic anhydride , a polymerization inhibitor hydroquinone dosage of 1% ( maleic anhydride quality as the base) , a reaction temperature of 140 ° C , a pressure of 1.5Mpa , butadiene and maleic anhydride molar ratio of 1.6 , the residence time of 0.8h conditions , MA conversion was 98.93% , tetrahydro phthalic anhydride product content of 96.86% , the exhaust butadiene content was 12.5% ??. Product solution was concentrated cooling crystallization extract the tetrahydro phthalic anhydride, crystal filtration and drying , the purity of 99.07% , a yield of 67.13% . 2 , in order to compare the different continuous and batch process , this paper further tetrahydrofuran as the solvent using the batch process synthesis Δ4-THPA. Examine the concentration of maleic anhydride , reaction temperature , time, molar ratio effect on the reaction and to determine the optimum conditions . Maleic anhydride concentration of 9% , a polymerization inhibitor hydroquinone dosage of 1% ( mass of maleic anhydride as the base) , the reaction temperature was 130 ° C , the reaction time is 60 min , butadiene and maleic anhydride molar ratio was 1.3 under the conditions of reaction pressure is not higher than 1.0MPa , the MA conversion rate of 99.63% , the Δ4 - THPA content 98.33% , exhaust butadiene content was 7.51 % . 3 as the Δ4-THPA the catalyst isomerization of to P 2 < / sub > O 5 < / sub > showed that the Δ4 - THPA the heterogeneous process can be divided into two stages , the first phase of the main reaction Δ4 - tetrahydro phthalic anhydride isomerized to the Δ3 - tetrahydro phthalic anhydride , the main reaction of the second phase of the Δ3 - tetrahydro phthalic anhydride isomerized to Δ1 - tetrahydro phthalic anhydride . Isomerization solidification of its components , as low as -25 ° C .
|