Experimental investigation of methanol steam reforming in multi-disk and packed-bed reactors with various supports using innovative catalysts

Today, energy demand is one of the fundamental determinants of economic development and social welfare. Dependence on fossil fuels creates significant challenges in terms of both sustainability and environmental impacts. In this context, hydrogen energy stands out as a clean, portable, and versatile energy carrier. Among hydrogen production methods, methanol steam reforming (MSR) is considered a strategic alternative, as it enables high hydrogen yields at relatively low temperatures. In this study, the performance of Cu/ZnO-based catalysts was investigated with respect to different support types, catalyst additives, and reactor designs, and new approaches were developed to improve efficiency in hydrogen production. Two different reactor configurations were designed and comparatively examined. The first was a packed-bed reactor, obtained by loading Cu/ZnO catalysts onto porous ceramic supports based on zeolite and kaolin. The second was a disk-type reactor, designed by coating aluminum disks in a single step using the spray pyrolysis method with various Cu/ZnO–ZrO2 catalysts. In the packed-bed reactor, supports with different porosity levels were produced through gelation and wet granulation methods, and the effects of Ca addition (5–20 wt%) were investigated. In the disk-type reactor, geometries with different passage diameters (1.0–1.4 mm) were prepared, and catalyst coatings were modified with ZrO2 at molar ratios of 2–8%. In the packed-bed system, the porosity, water absorption, and compressive strength properties of the gelation-based supports were modeled using machine learning algorithms. Following this modeling, SHAP (SHapley Additive exPlanations), ANOVA (Analysis of Variance), and LIME (Local Interpretable Model-agnostic Explanations) analyses were applied, which provided a deeper understanding of the interactions among system parameters. Based on the outcomes of these analyses, the wet granulation method was further developed and supports with different porosity levels and various Ca contents were prepared. Finally, MSR experiments were conducted for both systems, and methanol conversion, gas product distributions, hydrogen and carbon dioxide selectivities, and hydrogen yield were comprehensively evaluated. The results showed that zeolite-based supports achieved higher hydrogen production and conversion than kaolin, owing to their more regular pore structures. Ca addition enhanced hydrogen selectivity up to 15%, but higher addition levels reduced efficiency. In the disk reactor, disks with a passage diameter of 1.0 mm provided the highest conversion and selectivities, while ZrO2 addition in the range of 2–4% improved hydrogen yield. Furthermore, ANSYS-based flow analyses also offered supportive findings regarding the mixing performance of disk geometries. In the statistical evaluations, the Shapiro–Wilk test indicated that the data did not follow a normal distribution; therefore, non-parametric methods were preferred. The Mann–Whitney U test and Cliff's delta analysis revealed that zeolite-supported catalysts exhibited a statistically significant advantage over kaolin, particularly in conversion values. In addition, Spearman correlation analysis demonstrated a strong and positive relationship between conversion and hydrogen yield. In conclusion, this thesis identifies the key parameters affecting performance in MSR in terms of support materials, catalyst additives, and reactor design. The findings show that porosity, additive optimization, and reactor geometry play critical roles in hydrogen production. With original reactor designs that achieve high hydrogen selectivity and yield, this study provides insights into potential applications for future sustainable energy systems.