Theoretical studies of zeolites with Cu and Fe, for the direct conversion of methane to products

• Grant number: 22/05343-2
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: July 01, 2022
• End date: October 31, 2024
• Field of knowledge: Engineering - Chemical Engineering - Chemical Process Industries
• Principal Investigator: José Maria Correa Bueno
• Grantee: Ana Cristina Mora Tello
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Associated research grant: 18/01258-5 - Novel chemical catalytic and photocatalytic processes for the direct conversion of methane and CO2 to products, AP.TEM

Abstract

Recent advances in theoretical description of catalytic process concerning to partial oxidation of methane to methanol at low temperatures were achieved. The most promising issue regarding to catalyst process was obtained using copper-containing zeolite. It is possible to describe extended zeolites structure with DFT (density functional theory) calculations implemented in the following codes: TURBOMOLE, GAUSSIAN, VASP, MOLPRO, etc. However, a detailed molecular study of catalyst process imply in consider reduced systems in order to obtain precise quantum descriptions. The biggest theoretical difficulty to study these systems is associated to myriad of possibilities of initiating the microscopic process. However, the study can become feasible if the theoretical studies can be coupled to experimental data. Promising models must be inspired to experimental results. The possible initial attacks of methane to the copper/iron zeolite (e.g., mordenite) and the subsequent possible reactions can be inferred by microscopic theoretical studies. These final microscopic theoretical studies can give most precise description than experimental results. The complementarity between theoretical and experimental studies is the core of this synergism. Essentially the theoretical reaction path will be obtained choosing different initial attacks of methane and finding all energetically possible transition states with the neighborhood atoms. Less energetic transition states will be the most probably. The subsequent step depends on the rearrange of those transition states. That is, it is necessary to simulate all complete reaction paths in order to decide the most important routes. The addition of oxidant agent must be incorporate to the successive reaction path. The attack of this agent must be coupled to the neighborhood of the methane (bonded to the zeolite structure) by new transition states. The most important method to be used is the DFT in order to find useful results. If necessary, more precise results can be obtained by ab-initio correlated methods. However, the whole systems need to be reduced to give feasible results compatible to current computing resources. In relation to the microkinetic studies, it is necessary to conclude firstly the model and the quantum calculations discussed above to obtain the full mechanics of possible reactions. Several kinds of methods can be used, e.g., analytical (when possible) and deterministic and stochastic numerical procedures.Several technical questions must be solved. However, it is not impeditive for the success of the theoretical project. The most important aspect is to make appropriate connections between the theoretical and experimental researches. (AU)