Study On The Process Of Preparation Of Hydroquinone By Reduction Of P-benzoquinone

Hydroquinone is an important fine chemical raw material. It was widely used inmedicine, pesticide, dye, rubber, chemical fertilizer, water treatment and liquid crystalpolymer. The method of aniline oxidation mainly used for the hydroquinone which hasa certain market in the world, but this method with high consumption of materials,heavy workload of “three wastes” treatment and pollution, which limited thedevelopment of production heavily. This paper studied the electric field intensifiedmethod and catalytic hydrogenation method to solve the problem of low utilization rateof iron powder and large dosage of iron mud in the reduction process.To obtain higher utilization ratio of iron powder, the electric field was used in theacidic system and the reduction mechanism was studied. Comparative experiments werecarried out between the present industrial process and the electric field intensifiedmethod. It indicated that utilization ratio of iron powder was increased from28.57%to75.19%. The optimal parameters were obtained with the molar ratio of H2SO4/Fe was1/3and added it with the method of batch, voltage was3.0V, reaction time was2h, theutilization ratio of iron powder and the yield of hydroquinone were over75%and95%respectively.Comparative experiments were carried out between the Pd/C catalyst and theRaney Nickel catalyst in the hydrogenation process. It indicated that the activity of Pd/Ccatalyst was too high to control the hydrogenation process easily. However, the activityof Raney Nickel catalyst was mild and the reduction reaction can control easily. So theRaney Nickel catalyst was selected for hydrogenation catalyst in the reduction system.This paper studied the influence of catalyst dosage, reaction pressure, reactiontemperature, reaction time and dosage of solvent on the hydrogenation process whenRaney Nickel as hydrogenation catalyst. The optimal parameters were obtained with themass ratio of catalyst/benzoquinone was1/70, reaction pressure was2.00MPa, reactiontemperature was100℃, reaction timewas2h and the mass ratio ofbenzoquinone/solvent was1/50. The yield of hydroquinone and the selectivity ofhydroquinone were over97%and100%respectively. When the Raney Nickel catalystcontinuous used eight times under the condition, the yield of hydroquinone was also97%. It indicated that Raney Nickel catalyst showed good stability in the hydrogenationprocess. The electric field intensified method and catalytic hydrogenation method haveobvious improvement on technological process, material consumption andenvironmental protection, so there are technological and feasible process and good forindustrial production.