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Preparation of CBDO (3010-96-6) by hydrogenation of TMCB?

2017-12-25 来源:亚科官网
25 December 2017
  2,2,4,4-tetramethyl-1,3-cyclobutanediol, abbreviated as CBDO or TMCD. The copolyesters synthesized from CBDO have the characteristics of high inherent viscosity, high melt viscosity, high glass transition temperature and easy processing. They are suitable for home appliance manufacturing, automobile decoration, food packaging, medical supplies, water-based coatings and other field. There are many ways to synthesize CBDO, but the final step of all methods is the hydrogenation of 2,2,4,4-tetramethyl-1,3-cyclobutanedione (TMCB). So how to complete this step efficiently and cost-effectively?
  Researcher [1] prepared copper-based catalyst CuO-ZnO-Al2O3 by coprecipitation with low-cost copper and zinc as active components, and applied it to hydrogenation of TMCB to obtain TMCD. Specific methods are as follows:
(1) a certain amount of copper nitrate, zinc nitrate are dissolved in deionized water, mixed and transferred to a constant pressure dropping funnel;
(2) preparing a certain concentration of sodium carbonate and sodium hydroxide solution, moving to another constant pressure dropping funnel;
(3) disposing a 2% by weight aluminum hydroxide solution in a neutralizing beaker;
(4) The beaker was placed in a water bath at 65°C, control the flow rate and co-drop the above 2 kinds of solutions in constant pressure dropping funnel, stirr with a constant speed electric mixer, control the pH at about 8;
(5) CuO-ZnO-Al2O3 copper-based catalyst was prepared by standing and aging for 12h after dripping, filtering and washing, drying at 80°C for 5h and then calcining at 480°C for 4h, The mass fractions of CuO, ZnO and Al2O3 are 40%, 35% and 25%, respectively.
  The catalyst is used in the hydrogenation reaction of TMCB:
(1) 3.5g of catalyst is loaded in the middle of the reaction tube, and other parts are filled with ceramic balls;
(2) check the air tightness of the system, reduct with H2 at 300℃ for 1h;
(3) After reduction, the temperature of the catalyst bed is adjusted to the required value, the raw material TMCB in the storage tank is pumped into the preheater, preheated with the H2, and then enters the reactor, whereupon the catalyst contacts and occurs hydrogen reaction.
  After investigation, the optimum reaction conditions were as follows: reaction temperature 180℃, reaction pressure 4.0MPa, H2/TMCB (molar ratio) = 150 and TMCB mass space velocity 4h-1. Under this condition, the conversion rate of TMCB reached 96.1% and the selectivity of CBDO was 95.5%.
  Hydrogenation synthesis of TMCB to ptoduce CBDO, hydrogenation catalysts are mostly supported catalyst: the carrier is silica dioxide, aluminium oxide or silicon aluminum mixture, the active ingredient may be one or more of nickel, ruthenium, cobalt, cesium. Although activity of precious metal supported catalyst is high, but the cost is more expensive. Copper-based catalysts not only have good selectivity for carbonyl hydrogenation, but also have lower cost, high conversion and selectivity under suitable process conditions.
[1] Lou Yang, Zhang Yuanli, Shi Mingyan, et al. Study on catalytic synthesis of 2,2,4,4-tetramethyl-1,3-cyclobutanediol from 2,2,4,4-tetramethyl-1,3-cyclobutanedione. Petrochemical Technology and Application, 2015, 33, 405-407.
Edited by Suzhou Yacoo Science Co., Ltd.