Fanxing Li

This fundamental research is motivated by three major global challenges that directly involve the transformation of gas molecules: carbon dioxide (CO2) capture for greenhouse gas mitigation, CO2 conversion to fuels and chemicals, and nitrogen (N2) gas conversion to biologically available ammonia to meet growing fertilizer demand. The research focuses on creating and investigating multi-functional interfaces that durably immobilize enzymes near their gaseous substrates while simultaneously delivering essential chemical and electrical reducing equivalents and removing reaction products to achieve maximum catalytic rates. Biocatalytic systems to be explored are: conversion of CO2 to bicarbonate catalyzed by carbonic anhydrase, reduction of CO2 to formate catalyzed by formate dehydrogenase, and reduction of N2 to ammonia catalyzed by nitrogenase. We envision that minimization of reaction barriers near immobilized biocatalyst interfaces involving gas molecule conversions will lead to transformative innovations that help overcome global sustainability challenges.

Alkenyl benzenes such as styrene, (1,3 and 1,4) divinylbenzene (DVB), and alpha-methylstyrene (AMS) are important building blocks for rubber, plastics, and resin production. We propose to develop a transformative technology and catalysts to make the production of these molecules more efficient and less carbon intensive.

We propose an integrated technology of low capital intensity that will capture, utilize and sequester carbon dioxide in wood pulping processes. CO2 (Carbon Dioxide) will be utilized by converting two waste streams to mineral carbonate fertilizer. The carbon in the mineral carbonates is derived from carbon dioxide generated in recovery boilers and lime kilns. Excess carbon dioxide that is not utilized as fertilizer will be pumped deep underground into suitable geological reservoirs for permanent sequestration. Retrofitting lime kilns to oxy-fuel will enable low-cost generation of high purity carbon dioxide. If fully implemented at every large chemical pulp mill in the United States, approximately 14 million metric tons of carbon dioxide will be captured, utilized, and sequestered per year.

We propose to concurrently investigate two distinct methane pyrolysis approaches to co-produce hydrogen and easily separable value-added carbon products: (a) tailored heterogeneous catalysts for base-growth carbon nanotubes with selective base combustion for nanotube harvesting; and (b) molten phase catalysts that enables phase segregation of the carbon product. It is envisioned that approach a will be implemented in a circulating fluidized bed (CFB) system (related processes include CFB combustor or fluid catalytic cracker) and approach b will be implemented in a bubble column reactor (related processes include molten salt systems in nuclear power plants). These complementary approaches can facilitate low cost hydrogen production, facile catalyst-carbon separation, and different forms of value-added carbon products.

The objective is to develop a new, low-cost process intensified modular process to directly convert flare gas or stranded gas to carbon nanomaterials and co-product hydrogen (H2) with high conversion, selectivity, and stability.

Methane from shale formation has significantly increased the usable amount of this indigenous energy resource. Methane is commercially used as a feedstock for producing hydrogen and liquid transportation fuels via methane reforming processes. Although a large number of catalysts have been developed over the past century, deactivation of reforming catalysts, which can result from carbon formation, sintering, sulfur poisoning, or active metal oxidation, remains as a key challenge. The goal of this research is to investigate a unique family of core-shell redox catalysts that reforms methane via a cyclic redox scheme. The redox catalysts proposed have the potential to be robust, active, and highly efficient for methane partial oxidation without consuming gaseous oxidants such as steam or oxygen.

The increasing US shale gas supply has exerted significant pressure on natural gas prices. Over 200 billion ft3/year of natural gas is flared at remote production sites in the U.S. due to the limitations in transportation capacities and production fluctuations. Direct conversion of this currently wasted natural resource to transportable liquids is hampered by the difficulty of selectively activating methane. Dehydro-aromatization (DHA) has shown promise for the conversion of methane rich natural gas to benzene and other aromatics. However, this is an endothermic, equilibrium limited reaction. Our proposed concept avoids these limitations though structured multifunction catalysts that selectivity oxidize the byproduct hydrogen through a significantly intensified, chemical looping redox process. The proposed approach is particularly suitable for small-scale modular systems.

This project aims to investigate molten molybdate promoted perovskite oxides as a versatile core-shell redox catalyst platform for chemical looping – oxidative dehydrogenation (CL-ODH) of ethane and propane. Thin film model catalysts composed of perovskite oxide with alkali metal molybdate will be prepared and characterized in an ultra high vacuum surface reaction and characterization system.

We propose to use novel molten salt reaction media that are capable of: a. effectively capturing CO2 from power plant flue gases; b. utilizing the captured CO2 for oxidative dehydrogenation (ODH) of ethane, propane, and butane to produce value-added olefin and CO products. The abundant, low-cost ethane within the United States and the high value ethylene and CO products would drive down the costs for CO2 capture, leading to economically attractive systems for carbon management.

We propose to develop dual-phase perovskite oxide-molten salt (OMS) composites with tunable phase transition temperatures (e.g. 450 – 900 ˚C), ultra-high energy storage capacity (~650 kJ/kg), high temperature stability (e.g. 1200+ ˚C), and long storage duration for efficient utilization of high temperature industrial waste heat. This project will prepare these novel energy storage materials, evaluate their performance, and confirm their potential advantages.