The Changing Landscape of Hydrocarbon Feedstocks for Chemical Production Implications for Catalysis: Proceedings of a Workshop (2016) / Chapter Skim
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3 Catalytic Conversion of Methane
3 Catalytic Conversion of Methane
Pages 19-36
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From page 19... ...
At some point, it may be desirable to have economically viable processes for converting methane into ethylene and other value-added hydrocarbons, as well as processes that are more efficient than the current industrial methods for converting methane into syngas. Such a circumstance could arise, for example, if the demand for ethane outstrips the supply, if a new process made it economical to convert methane into transportable liquids for stranded gas (i.e., methane reserves that are too small and too far from current pipelines that are often flared or burned unproductively)
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From page 20... ...
. This model proposed FIGURE 3-1 Conversion efficiency and selectivity of oxidative coupling catalysts.
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From page 21... ...
that important steps in the reaction occur both at the catalyst surface and in the gas phase, though it did not explain how these steps (listed as 1–8; see Figure 3-2) fit together to yield the desired product.
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From page 22... ...
HYDROCARBONS TO CHEMICALS AND FUELS VIA ENGINEERED MICROBES In addition to the opportunities for chemical catalysis to contribute to the efficient use of the nation's shale gas reserves, researchers are making progress harnessing the power of biological systems to convert methane and natural gas liquids to value-added products. As Lercher noted, biological approaches have the potential to lower the energy costs associated with the high temperature regimes required for methane, ethane, and propane conversion using chemical catalysis.
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From page 23... ...
, and lipids may be produced at high concentrations without issues of toxicity to the microorganisms. Anaerobic consortia have the potential of methane activation at high efficiency, but they exhibit low rates and operate as a mixed culture whereby methane oxidation is coupled with sulfate reduction catalyzed by sulfur-reducing bacteria.
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From page 24... ...
An open discussion followed the four reports. Methane to Syngas In his introductory remarks, Jan Lerou, principal of Jan Lerou Consulting, briefly reviewed the major commercial technologies now used to convert methane into syngas, which then serves as a feedstock for ammonia, methanol, and hydrogen production.
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From page 25... ...
dry reforming.1 Each of these technologies has its own unique limitations and challenges, which if addressed satisfactorily would improve the economics of the processes using these technologies. Discussion Following the presentation, this group spent much of its time identifying four key objectives for research aimed at improvement of the available commercial processes, said Maria Flytzani-Stephanopoulos, distinguished professor and the Robert and Marcy Haber Endowed Professor in Energy Sustainability at Tufts University.
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From page 26... ...
Finally, this group felt that short-contact-time reactors have shown some promise, but there is still much to be done to achieve the level of process reliability required for an industrial process. Methane to Ethylene As Schomäcker had noted, oxidative coupling of methane to ethylene is technically feasible, but there are a number of features that at present make direct methane-to-ethylene processes uncompetitive commercially, a message reiterated in the introductory presentation by Bob Maughon, vice president for performance plastics and hydrocarbons research and development at The Dow Chemical Company.
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From page 27... ...
carries a higher raw material cost and capital burden, combining to make it uneconomical relative to reported ethylene price in Q3, but not in Q2. Oxidative coupling of methane (OCM)
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From page 28... ...
Among the top well-established research approaches for making methane-to-ethylene conversion viable, the group listed oxidative coupling, other oxidative routes, and non-oxidative coupling that would stop at ethylene rather than proceed to produce aromatic compounds, as well as routes based on first creating syngas from methane and using that as a feedstock for ethylene production. One of the promising but high-risk approaches being studied involves taking ethylene produced at a remote site and oligomerizing it to produce 1-hexene or 1-octene, value-added chemicals that could be readily transported.
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From page 29... ...
The catalyst is eventually deactivated by coke formation, though it can be completely regenerated by oxidation treatment in a second reactor. Discussion Following this presentation, the group's discussion, as reported by Monty Alger, director of the Pennsylvania State University's Institute for Natural Gas Research and professor of chemical engineering at Pennsylvania State University, started by identifying two reasons for why it would be desirable to develop industrial processes for converting methane to aromatics: the substantial price spread between methane and naphtha and the increasing demand for aromatics that is starting to outstrip capacity.
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Alger added that the working group discussed the possibility that environmental regulations to limit carbon emissions could make this technology attractive compared with today's alternatives. With regard to additional research that could improve this process and develop other routes for converting methane into aromatics, Alger said the group noted two major impediments: the lack of sustained research funding in the United States for this type of work and the shortage of good ideas in this area.
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From page 31... ...
Ipatieff Professor of Catalytic Chemistry and professor of materials science and engineering at Northwestern University, pointed out that creative catalytic chemistry must be paired with excellent engineering to develop an industrially useful process capable of supplanting the current indirect process that first converts methane to syngas and then on to methanol at a price of approximately $0.75 per gallon using Earthabundant catalysts. The main drawback to this process, which is practiced at a huge scale, is that it requires a significant amount of heat to produce syngas and the overall process capital cost intensity.
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From page 32... ...
, but any selectivity in the process was achieved at the expense of conversion and typical yields are 1 to 3 percent. Researchers at the Gas Technology Institute are reported to be developing a room-temperature, high-efficiency process to convert methane into methanol and hydrogen using metal oxide catalysts that are continuously regenerated.
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From page 33... ...
The group also noted that electrocatalytic methane activation is a new approach that highlights ways to think about entirely new concepts for catalyzing conversion of methane to methanol, and, in this arena, opportunities exist for more efficient energy production using direct methane fuel cells, but new catalytic materials are seriously lacking. The working group then discussed some of the challenges to making current approaches viable, starting with reducing the temperature of some of the reactions and improve their selectivity.
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From page 34... ...
Guido Pez, an independent consultant who retired from Air Products, noted that the U.S. Department of Energy funded a project that used a solid oxide-containing membrane as part of a methane oxidation scheme that did eliminate the importance for an air separation unit.
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From page 35... ...
In his opinion, research with the biggest potential for producing a breakthrough involves taking an entirely different approach to catalysis, such as the idea of combining different types of catalytic processes. Wachs added that the pulp and paper industry, the largest user of methanol as the feedstock for producing formaldehyde, strongly desires a one-step process for methane to formaldehyde or methane to methanol.
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From page 36... ...
36 CHANGING LANDSCAPE OF HYDROCARBON FEEDSTOCKS directly related to that invention. What is important, he said, is the crossfertilization among fields that results in knowledge generated in one field being applied to problems in another technology area where the market is demanding a solution.
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