Influence of the delamination of zeolitic imidazolate framework ZIF-7-III on the conversion of sucrose into methyl lactate

Abstract

The catalytic conversion of sugars to methyl lactate has been in the spotlight of the scientific community in the last decades. In this context, delaminated materials can provide better catalytic performances than their precursors, since they have a better accessibility to their active sites. In order to improve the yield to methyl lactate (ML), new delaminated material ZIF-7-III_EX was synthesized from the exfoliation of the dense Zn-based zeolitic imidazolate framework ZIF-7-III. Different techniques, namely XRD, SEM, TEM, thermogravimetric analysis and CO₂ adsorption, were carried out to characterize the obtained materials as well as to verify the exfoliation of the precursor. Regarding the catalytic results, as-synthesized ZIF-7 showed a promising yield to ML, 41.2 %, superior to that achieved by ZIF-9 (based on Co instead of Zn). In addition, the delaminated material ZIF-7-III_EX reached a ML yield of 69.1 %, which implies 67.7 % and 97.4 % of improvements with respect to ZIF-7 and to ZIF-7-III, respectively. The reuse of some selected catalyst materials derived from ZIF-7-III was also studied.