Kinetics of high pressure methanol synthesis

Kuipers, K.M. (2014) Kinetics of high pressure methanol synthesis. Master's Thesis / Essay, Chemistry.

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Abstract

In the exploration of renewable energy, biodiesel is coming forward as one of the leading solutions. Biodiesel is produced from a plant oil or fat and methanol, giving crude glycerol as a byproduct. One of the big advantages of biodiesel production is that a local feedstock can provide the required plant oil whereas methanol is a common platform chemical. Production takes place all over the world and its product is available at most European gas stations. Unfortunately, the rapid introduction of biodiesel to the market showed to have an influence on the selling price of its byproduct which decreased considerably between 2006 and 2010. Deterioration of glycerol prices could make biodiesel a lot less economically attractive for its producers. The Supermethanol project was initiated to develop a cost efficient process to reform crude glycerol to methanol in a two-step process by first reforming the glycerol to synthesis gas, followed by the conversion of synthesis gas to methanol. Methanol is produced on industrial scale at pressures between 5.0 and 10.0 MPa and formed via equilibrium reactions that requires the process to have a recycle stream back to the reactor. The synthesis gas obtained from the Supermethanol reforming process has an approximate pressure of 20.0 MPa, at this pressure the reaction equilibrium tends to full conversion. In addition, the formed methanol condenses in the reactor ensuring full conversion of the reactants. Without the necessity of a recycle stream, the methanol conversion process becomes less complicated and of smaller size which opens a window for implementation into an existing biodiesel plant. In this study a kinetic model was developed for the synthesis of methanol at pressures of 17.5 – 22.5 MPa based on experimental data obtained from experiments using a commercially available Cu/ZnO/Al2O3 catalyst. The formation of methanol and water was studied using varying feed compositions of CO, CO2 and H2 in a continuous spinning basket reactor by making use of an online gas chromatograph. Three kinetic models, based on a Langmuir-Hinshelwood/Hougen-Watson model and power law model were fitted to the experimental data. Finally, the best fitting model was found to give a relative average error of ∆R_(〖CH〗_3 OH)^' = 18.4 % for a temperature range of 483 to 498 K. Many kinetic models for the synthesis of methanol have been published over the last decades. Most of these are developed for low pressure methanol synthesis and are not applicable in the Supermethanol region. The kinetic model developed in this study can be considered the first of its kind.

Item Type:	Thesis (Master's Thesis / Essay)
Degree programme:	Chemistry
Thesis type:	Master's Thesis / Essay
Language:	English
Date Deposited:	15 Feb 2018 07:58
Last Modified:	15 Feb 2018 07:58
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/11986

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