Date of Award
4-23-2026
Thesis Type
PhD
Document Type
Thesis
Degree Name
Doctor of Philosophy (PhD)
Divisions
Faculty of Engineering
Department
Department of Chemical Engineering
Institution
Universiti Malaya
Abstract
The rapid increase in atmospheric carbon dioxide (CO2) concentrations due to extensive use of fossil fuels is a major contributor to global climate change. This challenge necessitates the development of technologies for CO2 capture and upcycling to value-added products such as methanol. However, CO2 conversion to methanol in traditional reactor (TR) with catalytic packed bed faces serious challenge of low reactant conversion due to thermodynamic limitations. In contrast, membrane reactors have developed to selectively remove products from reaction environment boosting the conversion. However existing designs still face challenges of structural integrity and scale-up complications. In this study, for the first time, a ceramic membrane microchannel reactor (CMMR) equipped with catalytic membrane was developed for CO2 conversion to methanol. To meet the design requirements of CMMR, a flat sheet Linde Type A (LTA) zeolite membrane was synthesized on macroporous alumina support via secondary growth method. During membrane synthesis, supports were seeded by an innovative pore-plugging cross-flow filtration technique, producing firmly anchored uniform seed layer over the entire surface without additional heat treatment. XRD and FESEM analysis confirmed that this approach produced membranes with comparable performance to those prepared with post-seeding heat treatment. Subsequently, catalytic membrane was fabricated by depositing a thin layer of CuO-ZnO-Al2O3 precursor over the pre-heated (50 ℃) membrane surface by dropping method using water-based suspension of precursor, followed by calcination at 360 ℃. FESEM and EDS analysis confirmed a well-defined layered structure of catalytic membrane with 45 μm thick catalyst layer and uniform distribution of metallic components. The CMMR was fabricated having 500 μm deep reaction channels for flow with tapered inlet and outlet headers. Computational fluid dynamic (CFD) simulations were performed using ANSYS Fluent to ensure the uniform flow distribution among all the channels. The best performance was obtained at 230 ℃ temperature and 4.0 MPa, yielding 86.28 % CO2 conversion, 57.49 % CH3OH selectivity and 49.60 % CH3OH yield. The obtained CO2 conversion was approximately three times higher than equilibrium conversion (27%), while ten times higher than traditional packed bed reactor (8.5%) and remarkably higher than existing membrane reactors for methanol synthesis. The enhanced performance of CMMR can be attributed to the high catalyst surface area provided by catalytic membrane and microchannel configuration which minimizes diffusion lengths while promoting the gas-catalyst contact. Although the best performance of CMMR was observed at 230 ℃ temperature and 4.0 MPa pressure, the optimal operating conditions were identified with in the temperature range of 210 – 230 ℃ and pressure of 3.0 – 4.0 MPa for reasonably efficient performance. The outcomes of this research showed promising results with potential of replacing the current industrial process of methanol synthesis while addressing the sustainable development goals as SDG-7, 9 and 13 for clean energy, industry innovation and climate action respectively.
Additional Information
Thesis (PhD) - Faculty of Engineering, Universiti Malaya, 2026.
Recommended Citation
Ullah, Aubaid, "LTA zeolite-based integrated ceramic catalytic membranes for methanol synthesis via CO2 hydrogenation in microchannel reactor systems" (2026). Student Works (2020-2029). 1997.
https://knova.um.edu.my/student_works_2020s/1997
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.
Included in
Catalysis and Reaction Engineering Commons, Materials Chemistry Commons, Membrane Science Commons
Initial
khm