Glycerol conversion to lactic acid (LA) was investigated in aqueous alkali over eight unsupported copper compounds (CuBr2, CuBr, CuCl2, CuCl, CuF2, Cu(NO3)2,CuO, and Cu2O) for studying the effects of anion and valence. Powder X-ray diffraction and scanning electron microscopy measurements indicated that these copper compounds were reduced to metallic copper with different morphologies. Divalent copper compounds exhibited much better performances than the corresponding univalent species, ascribed to their greater reduction heat and higher local reaction temperature. Divalent copper species activity, ionic radius, and the reported reduction potential decreased in the same order: bromide > chloride > floride ≫ nitrate. With increasing reaction temperature, catalyst amount, NaOH concentration and reaction time, glycerol conversion, and LA selectivity increased (due to by-product conversions to LA). Kinetic studies indicated that glycerol disappearance rate was first-order with respect to its concentration. CuBr2 had greater activation energy and therefore exhibited better performance than CuO when reaction temperature was greater than 155 °C. At 185 °C, CuBr2 reached 95.7% lactic acid yield and 98.65% glycerol conversion.

中文翻译：

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在碱性介质中，无载体的铜盐和大体积氧化铜将甘油转化为乳酸。

研究了在8种无载体铜化合物（CuBr2，CuBr，CuCl2，CuCl，CuF2，Cu（NO3）2，CuO和Cu2O）上的碱水溶液中甘油向乳酸（LA）的转化，以研究阴离子和化合价的影响。粉末X射线衍射和扫描电子显微镜测量表明，这些铜化合物被还原成具有不同形态的金属铜。二价铜化合物表现出比相应的一价物种更好的性能，这归因于其更大的还原热和更高的局部反应温度。二价铜的活性，离子半径和报告的还原电位按相同顺序降低：溴化物>氯化物>氟化物>硝酸盐。随着反应温度，催化剂用量，NaOH浓度和反应时间，甘油转化率的升高，和LA选择性增加（由于副产物转化为LA）。动力学研究表明，甘油消失率与其浓度有关。当反应温度高于155°C时，CuBr2具有更大的活化能，因此表现出比CuO更好的性能。在185°C下，CuBr2的乳酸收率达到95.7％，甘油转化率达到98.65％。