Reforming Reimagined: Plasma-Enhanced Dry Methane Reforming on Supported Pt Catalysts

Abstract

The increasing global demand for hydrogen (H2) as a clean energy carrier underscores the urgency of developing sustainable H2 production methods. Although widely used, conventional steam methane reforming (SMR) is carbon-intensive, spurring the exploration for alternatives. One promising route is dry methane reforming (DMR), which utilizes carbon dioxide (CO2) and methane (CH4), two potent greenhouse gases, to produce syngas (carbon monoxide (CO) + H2). However, DMR's high-temperature requirements and catalyst deactivation via coke formation hinder its practical implementation. This thesis investigates plasma-assisted DMR as a low-temperature alternative, leveraging non-thermal plasma (NTP) to activate reactants at milder conditions. A coaxial dielectric barrier discharge (DBD) reactor was employed to evaluate Pt catalysts supported on alumina (Al2O3), silica (SiO2), and zeolite 3A synthesized via incipient wetness impregnation. Catalyst characterization by N2 physisorption, CO diffuse reflectance IR Fourier transform spectroscopy, transmission electron microscopy, CO pulse chemisorption, and thermogravimetric analysis revealed that Pt dispersion and stability was influenced by the support, with larger surface area supports exhibiting higher Pt dispersion. While Pt/SiO2 had complete selectivity for CO and H2 in thermal DMR, Pt/Al2O3 and Pt/3A also facilitated the reverse water-gas shift (RWGS) reaction, as evidenced by H2O formation. CO and H2 formation rates were enhanced by the NTP even at low temperatures on metalfree and metal-loaded supports, and ethane (C2H6) was also formed, although to a lesser extent when Pt was present. Plasma power and product formation rates on metal-free supports were linked to support dielectric properties, which influenced plasma behavior and homogeneity. Post-reaction analyses demonstrated minimal coking and NP sintering for supported Pt catalysts and, in some cases, improved NP size uniformity. This study demonstrates that combining NTP with engineered Pt catalysts can reduce temperature requirements, produce new products, and mitigate catalyst deactivation in DMR, providing a promising route for decentralized, electrified methane reforming that also serves to valorize CO2. These findings advance the understanding of plasma-catalyst interactions and contribute to the design of sustainable, low-carbon hydrogen production technologies.