(551c) Maximizing Conversion and Coking Stability for Hydrogen Production Via Dry Reforming of Methane over a Ni/Zeolite Catalyst

Global energy demand keeps rising due to increasing human population. As a result, there is a need to find alternative ways of producing energy for human use aside from fossil fuels. Hydrogen generation from biomass is one effective and sustainable way to contribute to increasing energy production. Although different processing techniques are being used recently, dry reforming remains an interesting innovative technique as it utilizes two greenhouse gases (Methane and Carbon dioxide), thus contributing to lowering carbon emissions. Deactivation, stability, cost, and selectivity are some of the primary difficulties that heterogeneous catalysis for dry reforming of methane (DRM) faces. A more competent way of producing catalysts is now ongoing in recent catalysis work.

The performance of catalysts used for the dry reforming of methane strongly depends on the synthesis method, selection of active metals and supports as well as reaction conditions. Acid and basic sites of catalysts also play an important role to reduce coking and enhance catalyst stability. If the catalyst is more basic, it improves the activation of CO2 which is acidic, thereby reducing carbon deposits on the catalyst, which are the primary mode of catalyst deactivation. My research focus is on using low cost and effective Ni metal catalysts and zeolite as a support. Specifically, I am using a clinoptilolite zeolite mined in Winston, NM. In general, zeolites have good properties such as high surface area, high porous structure for cations, and good stability at higher temperatures. They are mostly used for removing heavy metals from wastewater, and also as a catalyst for other pharmaceutical and petrochemical processes. Though some work has been done using zeolites as supports for dry reforming of methane, this is the first time the Winston Zeolite has been investigated as a catalyst support.

A 5% Ni/zeolite catalyst was synthesized using incipient wet impregnation, after which thermo-gravimetric analysis was carried out to know at which temperature the nitrate will decompose to oxides. Temperature programmed desorption was performed using hydrogen to reduce the oxides to get metallic Ni on zeolite. The temperature at which the NiO reduced to Ni was at 450oC. To know how well Ni metal is dispersed on zeolite, Hydrogen chemisorption was carried out to compare zeolite support with Al2O3 and CeO2 after TPD. According to results, zeolite support showed higher dispersion of Ni metal with smaller active particle diameter as compared with Al2O3 and CeO2. The acidic and basic sites of zeolite were analyzed using CO2 - TPD within a temperature range of 35oC to 600oC. Highest peak was seen at a temperature around 600oC indicating that zeolite has a strong basic site. NH3 - TPD was also conducted within a temperature range of 35oC to 600oC, with a low weak acidic peak at the initial temperature, indicating that it has weak acidic sites.

Future plans will be to react this catalyst with CH4 and CO2 to produce H2 and CO at 600°C - 800°C. Other analysis that will be conducted on the catalyst includes; surface area determination using BET, XRD for crystal and structure of catalyst, Pyridine FTIR analysis to determine types of acidic sites, and Temperature-Programmed Oxidation to know the amount and type of carbon formed on the catalyst. Alternate way of synthesizing catalyst will also be compared with the incipient wet impregnation method. This will help us modify and improve on the catalyst properties to ensure low deactivation, and high efficiency.