The direct methane to methanol transformation has been a topic of intensive research for many decades. The challenging activation of methane along with the potent overoxidation of methanol at high temperatures renders the development of an efficient catalyst and an industrial process particularly challenging. This thesis aims to extend the understanding of the direct methane to methanol (DMTM) transformation over copper-exchanged mordenite and to suggest an industrially viable process inspired by the findings.
A series of experiments led to the development of a laboratorial process over a 3% wt. copper Mordenite catalyst (CuMOR), which maximises the methanol (CH3OH) yield. The suggested step-wise process involves three subsequent steps, specifically a catalyst activation step, a CH4 pre-adsorption step and a reaction and CH3OH desorption at 200oC.
A kinetic study of the reaction was carried out. Kinetic equations were derived based on experimental and literature data about the reaction. A model with an added associative CH4 desorption term provided the best fit to the experimental data, while having direct physical meaning. The apparent activation energy of the process was calculated with help of an Arrhenius plot.
An industrial application of the process was conceptualised and modelled. A technoeconomic evaluation of the project revealed that under current catalyst performance, the process could never achieve profitability. A comparison of different case scenarios for the performance of the catalyst led to the conclusion that a 40-fold more efficient catalyst is the ideal target for future research with 2.5 years of payback time.
Finally, the role of the eight membered rings (8MR) of zeolites in the DMTM was investigated. 4 zeolitic frameworks (Gismondine, Phillipsite, Merlinoite and Edingtonite) containing 4MR and 8MR were synthesised and tested in the reaction. Only the Edingtonite (EDI) framework was able to produce 4.6μmol of CH3OH per gram of catalyst throughout the duration of the experiment, while conclusions were reached regarding the effect of the Si/Al ratio and the zeolite topology on the DMTM.