Zr-Ce/VPO催化剂制备及环己烷气相氧化合成己二酸的工艺研究

采用Zr/Ce复合氧化物改性钒磷氧化物(VPO)制备Zr-Ce/VPO催化剂,开发环己烷气相氧化一步法合成己二酸工艺,考察了反应温度、氧气进气量以及乙酸添加量对环己烷气相氧化工艺的影响,并在微型固定床氧化反应器上评价了催化剂性能。结果表明:采用Zr-Ce/VPO催化剂可催化环己烷经气相氧化一步法合成己二酸;使用乙酸可改善催化氧化的微观环境,提高环己烷的转化率及己二酸选择性;己二酸合成优化工艺条件为反应温度200℃,氧气、氮气流量各10 mL/min,乙酸与环己烷按1∶4(质量比)混合,混合物进料量93.6 mg/min,系统压力0.3 MPa,此时,环己烷的转化率达到8.9%,己二酸选择性达到33.9%。

Study on preparation of Zr-Ce/VPO catalyst and process of cyclohexane to adipic acid by gas phase oxidation

A Zr-Ce/VPO catalyst was prepared by using Zr/Ce compound oxide to modify vanadium phosphorus oxide(VPO), and direct synthesis of adipic acid from cyclohexane by gas-phase oxidation was developed. Reaction conditions including temperature, oxygen intake and the amount of acetic acid were optimized. The catalyst was evaluated in a micro fixed bed oxidation reactor.The results showed that the Zr-Ce/VPO catalyst could effectively catalyze the direct oxidation of cyclohexane to adipic acid in gas phase. The addition of acetic acid could improve the micro environment of catalytic oxidation, and enhance the conversion of cyclohexane and selectivity towards adipic acid. The optimum conditions for the synthesis of adipic acid were as follows: reaction temperature 200 ℃,system pressure 0.3 MPa,flow rate of oxygen and nitrogen 10 mL/min respectively,feeding rate of the mixture of acetic acid and cyclohexane(1∶4, mass ratio) 93.6 mg/min. The conversion of cyclohexane was 8.9%, and the selectivity of adipic acid was 33.9% under optimized conditions.