Over the course of the 2-day workshop, the presentations and discussions in the breakout groups highlighted several key points and broad challenges and opportunities where advances in catalysis could enable optimal use of the nation’s shale gas for the benefit of the chemical industry. Many of the key points captured from individual breakout groups overlapped one another. These key points are summarized here.
As discussed in the opening chapters of this Proceedings of a Workshop, reevaluating the focus of research in catalysis was inspired from the current shift in petrochemical feedstocks to lighter hydrocarbons. This shift is a result of technological advances in hydraulic fracturing and horizontal drilling that have enabled access to abundant reserves of natural gas. In evaluating what this new research focus might look like, other important factors were mentioned at the workshop. Chief among these include lowering energy and resource intensive catalytic processes, with a particular focus on reduced carbon dioxide emissions.
During the course of the workshop, several routes were identified by which methane or other light alkanes could be converted to higher-value chemicals. The most promising routes involve the conversion of the light alkane (principally ethane and propane) to olefins. The development of a commercially viable process for the direct conversion of methane to higher-value chemicals was recognized to be a continuing challenge notwithstanding impressive research and technological advances made in recent years. It was also recognized that further research, both with regard to the design and development of catalysts, reactors, and overall process
schemes, can contribute in achieving economically viable processes, a goal to be pursued vigorously in order to maintain the competitive advantage that shale gas offers the U.S. chemical industry.
Many of the research opportunities identified and discussed among participants during the workshop are not unique to lighter feedstocks. Nevertheless they remain important challenges to address in order to enable the development of successful catalytic processes for these feedstocks, as well as to benefit the field of catalysis more broadly. These research opportunities include
- A concerted basic research effort combining kinetics, spectroscopy, and theory aimed at increasing understanding of the catalytic process on an atomic and molecular level that could be used to guide the development of catalysts with precisely tailored properties that can retain their integrity under industrial operating conditions.
- Development of advanced analytical capabilities to enable the structural and chemical characterization of catalysts in a temporally and spatially resolved manner and under realistic operating conditions.
- Design and development of more selective catalysts that produce fewer byproducts and thereby reduce the energy demand and capital costs for post-reaction separations.
- Identification of ways to manage carbon flow so that carbon ends up preferentially in products rather than in coke. Increased understanding and new approaches for solving this issue would increase reaction productivity, reduce energy use, and extend catalyst lifetime.
- Increased collaboration among materials scientists, chemists, and reaction engineers working in industrial, academic, and national laboratories in order to accelerate the development of highly selective and robust catalysts that could withstand real operating conditions.
- A portion of the national research portfolio devoted to novel, high-risk approaches would enable transformative discovery and technology.
In addition to the general research challenges for catalysis, research challenges and opportunities that are specific to lighter feedstocks were identified. Earlier chapters in the report provide details on previous and current research approaches to address the catalytic conversion of methane and light alkanes. However, ongoing research efforts to maximize the full potential for catalytic conversion of methane and light alkanes were mentioned. Those captured during the workshop include
- acquiring fundamental knowledge that would enable the rational design of selective and stable catalysts for conversion of methane and condensable components of natural gas to chemical intermediates, in particular, C4 alkenes and dienes and aromatics;
- novel (small-scale catalytic) processes to convert natural gas streams associated with untapped reserves of stranded gas;
- identifying and developing new oxidants that can replace oxygen, but be easily produced from oxygen (or, more ideally, air) in alkane oxidation reactions and new processes for managing oxygen in a cost-efficient manner;
- researching a detailed understanding of chemical looping and using that knowledge to develop novel catalysts and reactor designs to enable a more efficient approach to methane utilization;
- exploration of biosynthetic routes for converting methane into entirely new materials with novel properties;
- applying metabolic engineering to boost yields from microorganisms capable of converting methane into chemicals with no carbon dioxide production;
- investigating processes that couple biocatalysis with electrocatalysis to convert methane to chemicals without carbon dioxide or water production;
- identifying single-site catalysts that enable continuous conversion of methane to methanol; and
- studying metal-organic frameworks as potential solutions to the challenges of separating products from reactants in an energy- and cost-efficient manner.
To realize the greatest potential of recently more available and increasingly lower-cost natural gas as a feedstock for chemical production requires finding new catalysts that exhibit higher stability and selectivity with fewer byproducts than those currently available. Combined with novel product-separation approaches, cost and energy-efficient processes may be achieved. Participants noted that even with better design and improved engineering processes, a remaining problem is the production of greenhouse gases. To move toward a low carbon world, much of what happens in the future is dependent on thinking holistically and creating catalysts that assist in the transformation of natural gas to higher value chemicals while reducing any negative environmental effects. The pursuit of this challenge will be accelerated by collaborations among chemists, chemical engineers, materials scientists, physicists, and biologists from academia, industry, and national laboratories.
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