1. Development of Cost-Effective Technology for Biogas Purification
Biogas, primarily a mixture of CH4, CO2, N2, H2S, is a renewable source of methane (CH4). Bio-methane extraction from biogas to make it pipeline-quality gas is of interest to electric utilities because renewable gas counts as CO2-net neutral fuel and qualifies for carbon credits. This proposed study is focused on developing an economical method to produce clean methane from landfill gas. Our ongoing collaboration with the USDA-ARS center in Florence, South Carolina on biomass pyrolysis shows that the availability of biochar from pyrolysis could be an opportunity to remove unwanted elements form biogas produced from landfills. The recovered bio-methane could potentially displace about 10% of the imported natural gas used to produce electricity on Long Island.
2. Ethanol-Water Separation Using Pervaporation Membranes
New breakthroughs on thin-film nanofibrous composite (TFNC) membranes for water purification, including the use of ultra-fine cellulose nanofibers (diameter ~ 5 nm) and the development of multiple-jet electrospinning technology (nanofiber diameter 100 - 300 nm), have provided promising pathways in the filtration field. The non-woven structure has interconnected pores and very large surface-to-volume ratio, while the ease of surface modifications for cellulose can open up interesting leads for many biomedical and industrial applications. This membrane technology is being developed for pervaporation in ethanol synthesis by fermentation process to separate alcohol and water in a much more-energy efficient manner, which is the focus of this study. It is known that the cost of dehydrated ethanol by azetropic distillation is about twice higher than that of the pervaporation technique. The increase in membrane permeation rate can yield further energy reduction benefit.
3. Upgrading of Biomass-derived Bio-oil to Drop-In Replacement Renewable Hydrocarbon Fuels
One of the pathways for biomass conversion of interest is pyrolysis that offers feedstock densification at the source making it economical to transport the otherwise wet feedstock. However, the dense bio-oil (or pyrolysis oil) requires further processing to make it usable as transportation or power generation fuels. Previous and several ongoing studies, reported in literature, focus on bio-oil production via either slow or fast pyrolysis. In the latter method, the residence time is kept to a fraction of a second to minimize undesirable biochar and gaseous products while enhancing the bio-oil yield. The detailed characterization of bio-oils is reported. Several companies are conducting studies to develop a catalyst system capable of economical processing of renewable hydrocarbon fuels from bio-oils. The focus is to eliminate O in bio-oil as CO2 or H2O in the product slate while facilitating catalytic production of hydrocarbon fuels of interest, namely diesel.
4. Catalytic Conversion of C5/C6 Carbohydrates in Furan Derivatives.
It has been estimated that by 2030 lignocellulosic biomass could supply a substantial portion of the international chemical and transportation fuel market. While lignocellulose is cheap and abundant forms of biomass, it is difficult to convert to target materials due to the high crystallinity structure and oxygen/carbon ratio. In order to increase the biomass conversion and upgrade bio-oil into fuels (green diesel) and chemicals, oxygen reduction and chemical bonding rearrangement are crucial. Furan derivatives, such as 5-Hydroxymethylfurfural (C6H6O3, HMF) and furfural (C5H4O2, furan-aldehyde) are industrially produced via acid-catalyzed dehydration of glucose or fructose and xylose, respectively, and have been considered as an important furan commodity and building block. Our proposed research plan aims to control the conversion of lignocellulosic biomass into furan derivatives which are subsequently converted into bio-fuels and bio-chemicals by catalytic hydrodeoxygenation (HDO) reaction. We propose to initially explore a model compound, understand the catalytic activity and catalyst surface reaction mechanisms. In addition to the fundamental research, we will develop a new methodology for a direct conversion of biomass into fuels and chemicals for an industry application. In order to make the technique better suited for industrial applications and establish the fundamental understanding of HDO reaction of lignocellulosic biomass derived chemicals, we will perform the several stages investigations; 1) novel catalyst synthesis, 2) in-situ catalytic activity test varying temperature and pressure, 3) catalyst surface characterization and 4) feasibility of using catalyst with industrial applicable reactors, such as a fluidized-bed and fixed-bed reactor.
5. Development of a Flex Bio-Plant: Microemulsion-based production of bio-methanol and bio-butanol from biomass-derived synthesis gas
The slurry-phase MoS2 catalyzed process to produce mixed alcohols shows that the system operates as a 4-phase system (catalyst/solvent/aqueous/gas) limiting mass transfer to produce mixed alcohols in low yields. The ongoing work envisions a microemulsion system in which the dispersed oil phase in water medium functions as a reservoir of nano-containers for the MoS2 catalyzed reactions. The CO2 in syngas, present in supercritical state under operating temperature and pressure, itself acts as the dispersed oil phase and is solubilized in a water medium using non-ionic surfactants. This would substantially enhance alcohol production rates through higher catalyst /gaseous reactant contact in the oil phase and excellent heat management through the dispersion medium. Also, selective partitioning of heavier products in to the oil phase helps in reducing the downstream fractionation load of mixed alcohols. The proposed partnership brings together expertise of two NSF centers: the Center for Advanced Studies in Novel Surfactants (ASNS) is formulating MoS2 containing microemulsions that can be stable under operating temperatures and pressures and CBERD is conducting tests to evaluate the prepared microemulsions for mixed alcohols. A successful system would achieve the CO conversion per pass from < 20% to > 50% making this pathway a potential commercial process.
6. Mining Methane Hydrates Coupled with Carbon Dioxide Sequestration
Global hydrate deposits in marine and permafrost locations are estimated to contain 700,000 tcf methane that is more than all other combined sources of natural gas. However, the marine sediment matrix that contains hydrates could lead to seafloor instability if methane was mined. Supplementary to this issue is the looming climate change issue that may dictate that the rising global atmospheric temperatures must be contained to below 2oC (2 Degree Scenario (2-DS)) for effective carbon management. Since fossil fuels are projected to keep 74% of the energy consumption share in 2035 (IEA projections), a cost-effective CO2 sequestration method would help the 2-DS target. It is known that hydrates of CO2 are more stable than CH4- this property would allow a scheme that involves pumping CO2 in natural CH4 hydrate reservoirs to release CH4 while trapping CO2. We are investigating sediment-hosted hydrate formation and dissociation kinetics of both CO2 and CH4 molecules at micro and macro scales. For macro studies, the work is performed in the Flexible Integrated Study of Hydrates (FISH) unit at Brookhaven National Laboratory (BNL). The micro work is being performed at Beamline X-2B at the National Synchrotron Light Source (NSLS) using micro computed tomography (CMT) by imaging in situ hydrate formation/dissociation phenomenon. Both approaches are yielding data that is useful in formulating an economical CO2 sequestration scheme.
7. Photon induced hydrogen and hydrocarbon fuel production
One of the most attractive and economical ways of photon energy storage is conversion to chemical fuels. Main research direction is simplified model device fabrication and fundamental level studies for the photon induced production of fuels (Hydrogen, Hydrocarbons) from water and/or carbondioxide. Convenient starting point is to directly produce Hydrogen by splitting water and indirectly produce hydrocarbons via reduction of atmospheric carbondioxide. However, higher level device should be essentially composed of artificial nanoscale complex assemblies, mimicking and replacing biomass to directly produce hydrocarbons within the nanoscale architectures. Background works performed up to date are photon induced hydrogen production at ~2% efficiency as demonstrated by dispersed metal oxide catalyst particles in water-methanol solution. In addition, it has been shown that pulsed/modulated heating allowed orders of magnitude higher Hydrogen production rate without causing detrimental boiling of entire solution by imposing extreme reaction condition only to the solution at the periphery of nano-catalysts. The on-going efforts include optimization of catalytic particles configuration in porous matrix form and advanced diagnostics of transient reaction behavior.