Molecular design of carbon dioxide coupling with ethylene catalysts.

Identifier:  TFG:131

Handle: https://hdl.handle.net/20.500.11797/TFG131

Authors:  Solé Daura, Albert

Abstract:
Disseny molecular de catalitzadors per l’acoblament de diòxid de carboni amb etilè. ABSTRACT ALBERT SOLÉ The acrylate formation via homogeneous metal-assisted coupling reaction between CO2 and ethylene has been a target to achieve for a long time, because the chemical industry wants to produce commodity chemicals by the most economically and sustainable way as possible. Nickelalactones are the key intermediate that may decompose through β-H transfer process, which is the rate-determining step of the catalytic cycle. In order to avoid the high potential energy barrier for this step, due to the strain imposed by the 5-membered ring of the metallacycle when it has to distort itself to reach the TS geometry, we explore the utilization of unprecedented bimetallic catalysts for this reaction. The hypothesis in which we rely our work is that an additional metal center could promote the hydrogen abstraction without ring strain. Herein we describe the process we have followed to design that new catalysts and the subsequent computational study of the β-H transfer process pathways from the corresponding nickelalactone carried out by DFT. For simple bimetallic models we have found out lower values for potential energy barrier associated with the β-H transfer process, compared with the already elucidated values for the monometallic cases. These facts are encouraging, but when we studied the PES for more realistic catalysts we dealt with higher potential energy barriers in approximately 50-60 kJ·mol-1 than those of monometallic cases. We have also studied the thermochemistry for the metallalactone formation and the posterior β-H transfer reaction for monometallic catalyst built on other transition metal centers, including Mo, W, Pd, Pt and Fe. This exploratory study has revealed some trends than can be used for further attempts of catalyst design. Encouraged by the knowledge gained, we will use this work to write down a research proposal that will be presented to TOTAL ENERGIE DEVELOPPEMENT S.A.S. for the sponsoring of a master/Ph.D. grant.