U Mass team develops improved catalyst for catalytic fast pyrolysis boosting petrochemical output from biomass by 40%
|The new catalyst boosts the output of olefins and aromatics from biomass by 40%. Credit: Cheng et al. Click to enlarge.|
A team at the University of Massachusetts Amherst, led by George Huber, has developed a new bifunctional catalyst (Ga/ZSM-5) that displays increased selectivity for the production of aromatic compounds during the catalytic fast pyrolysis (earlier post) of biomass.
With this gallium-promoted ZSM-5 catalyst, olefins such as ethylene and propylene, which are produced as intermediates, are more efficiently converted into aromatics, especially benzene. Ga/ZSM-5 also promotes decarbonylation and olefin-aromatization reactions. Overall, the new catalyst boosts the yield for five of the six key chemical building blocks—benzene, toluene, xylene, ethylene and propylene—from biomass by 40% compared to previous methods.
Benzene, toluene, and xylene are aromatics; and ethylene and propylene are olefins. Olefins are used in plastics, resins, fibers, elastomers, lubricants, synthetic rubber, gels and other industrial chemicals. Aromatics are used for making dyes, polyurethanes, plastics, synthetic fibers and more. Methanol is the only one of the six key petrochemicals not produced in that same single-step reaction.
In this single-step catalytic fast pyrolysis process, either wood, agricultural wastes, fast growing energy crops or other non-food biomass is fed into a fluidized-bed reactor, where this feedstock pyrolyzes to form vapors. These biomass vapors then enter the team’s new gallium-zeolite (Ga-ZSM-5) catalyst, inside the same reactor, which converts vapors into the aromatics and olefins.
The economic advantages of the new process are that the reaction chemistry occurs in one single reactor, the process uses an inexpensive catalyst and that aromatics and olefins are produced that can be used easily in the existing petrochemical infrastructure.
The new process was outlined in a paper published in the 23 Dec. 2011 edition of the German Chemical Society’s journal Angewandte Chemie. It was written by Huber, Wei Fan, assistant professor of chemical engineering, and graduate students Yu-Ting Cheng, Jungho Jae and Jian Shi.
The research reported in Angewandte Chemie uses the same catalytic fast pyrolysis reactor for turning biomass into aromatics and olefins that was described in the 26 November 2010, edition of Science, but with the added dimension of the new gallium-zeolite catalyst. (Earlier post.)
The process has been tested and proven in a laboratory reactor, using wood as the feedstock, the research team says.
We think that today we can be economically competitive with crude oil production. The ultimate significance of our research is that products of our green process can be used to make virtually all the petrochemical materials you can find. In addition, some of them can be blended into gasoline, diesel or jet fuel.
The whole name of the game is yield. The question is what amount of aromatics and olefins can be made from a given amount of biomass. Our paper demonstrates that with this new gallium-zeolite catalyst we can increase the yield of those products by 40 percent. This gets us much closer to the goal of catalytic fast pyrolysis being economically viable. And we can do it all in a renewable way.—George Huber
The new production process has the potential to reduce or eliminate industry’s reliance on fossil fuels to make industrial chemicals worth an estimated $400 billion annually, Huber says. The team’s catalytic fast pyrolysis technology has been licensed to New York City’s Anellotech, Inc. (earlier post), co-founded by Huber, which is scaling up the process to industrial size for introduction into the petrochemical industry.
Yu-Ting Cheng, Jungho Jae, Jian Shi, Prof. Wei Fan and Prof. George W. Huber (2011) Production of Renewable Aromatic Compounds by Catalytic Fast Pyrolysis of Lignocellulosic Biomass with Bifunctional Ga/ZSM-5 Catalysts. Angewandte Chemie International Edition. doi: 10.1002/anie.201107390