Proposal Number: CBET-0708932 Principal Investigator: Fernando, Sandun D. Institution: Mississippi State University In order to address present limitations of catalytic hydrogen production from biomass, there will be investigated an alternative, innovative paradigm where electrically charged viscous liquid droplets will be reformed when they are between 1-100 nm in diameter, i.e, nanophase reforming. The factors impeding development of this technology are the gap in the knowledge of the chemistry that occurs at the positively charged substrate and the negatively charged catalyst/support interface and how viscous nanoscale droplets interact with solids.Both experimental studies and theoretical modeling and simulation will be conducted in an integrated study to understanding this behavior, with the ultimate goal of enhancing the nanophase reforming technique. Renewable raw materials which are CO2 neutral such as lipids, carbohydrates and their derivatives have high molecular weights and are highly viscous and the existing hydrogen production technologies, i.e, steam reforming and aqueous phase reforming (APR), are not highly effective in reforming such fluids. However, APR is advantageous in several ways over steam reforming: APR 1) requires less overall energy by saving the latent heat of vaporization; 2) has the ability to reform at substantially lower temperatures and 3) has the ability to harness the full potential of the water gas shift reaction which is thermodynamically inhibited at steam reforming temperatures. Despite the above advantages, APR is hindered by slow hydrogen production rates mainly due to diffusion resistance around the solid (catalyst) layer. Steam reforming, although it has historically resulted in high hydrogen yields from short chained hydrocarbons, is ineffective in reforming of viscous substrates due to mass transfer limitations associated with changing the state from a liquid (droplets > 100 nm) to a gas (particles < 1 nm). This leads to our proposed study of catalytic reforming of charged liquid nanodroplets of 1 to 100 nm in diameter. The long-term goal is to develop a reforming technique to produce hydrogen primarily from biorenewable feedstock which has markedly different physiochemical properties than petroleum based hydrocarbons. The objective of this application is to improve the basic understanding of the chemistries involved in catalytic reforming of positively charged substrate droplets over a grounded Ni/carbon-graphite conducting catalyst surface. The central hypothesis of the study is that reforming electrically charged substrate droplets that are between 1-100 nm in diameter can significantly increase substrate conversion in comparison to the conventional APR process. The rationale and the intellectual merit of our hypotheses is that if the reactants are split into finer droplets and electrically charged, the reactant densities could be reduced while allowing the positively charged reactant droplets to be attracted to the negatively charged catalyst support, thus instigating much higher substrate availability at the catalyst active sites than that of APR. We have obtained preliminary data using our electrosplitting device to demonstrate that the production of nanoparticles from highly viscous glycerin is possible. The central hypothesis will be tested by pursuing the following specific aims: 1. Production of glycerin nanoparticles with a consistent profile - Input parameters: fluid flow rate, fluid density, permittivity of free space, surface tension and conductivity properties of the fluid affect the droplet size distribution of the nanospray. A droplet size distribution that consists of 50 nm diameter droplets will be obtained by changing aforementioned parameters. 2. Comparing the hydrogen selectivity, glycerin conversion and byproduct formation - These parameters will be measured for APR, steam reforming and nanophase reforming while keeping catalyst loading, catalyst surface area and feed flow rates constant through out all experimental runs. 3. Proposing reaction mechanisms with the help of product identification in the condensates - The products of the condensate will be analyzed through GCMS, HPLC and LCMS to determine the reaction mechanisms.
Quantum chemical calculations will be performed and complementary simulations developed, followed by experimental validation to screen possible catalysts. Depending on these results, another catalyst might be added into the experimental design for a more accurate evaluation of this concept. The results should be applicable to a broad range of other liquid bio-products, such as carbonaceous triglycerides and their derivatives. This research may help broaden the raw material choices available for future hydrogen based energy systems. Research will be incorporated into education, and one doctoral student and one minority and underrepresented student will be trained.
