Efficient hydrotalcite-based catalyst for acetone condensation to α-isophorone -: scale up aspects and process development

It is previously known that the thermal decomposition of Mg/Al hydrotalcite precursor results in a catalyst that yields the highest ratio of isophorone/mesityl oxide during aldol condensation of acetone. This work describes the catalyst scale up and process development starting from the Mg/Al precursor aimed at maximizing the alpha-isophorone production and minimizing feed loss to heavies. Selectivity to isophorone was shown to be inversely proportional to the catalyst particle size. A compromise between smaller desired particle size and the associated increase in pressure drop was achieved by adding macroporous diatomaceous earth to the extrudates. Addition of up to 40% macroporous diatomaceous earth improved the alpha-isophorone selectivity of the extruded catalyst. Intermediate products, such as mesityl oxide and beta-isophorone, could be successfully recycled to further increase the a-isophorone yield. (C) 1998 Elsevier Science B.V. All rights reserved.