Chemical engineers from the University of Massachusetts Amherst, using their own licensed catalytic fast pyrolysis process for transforming renewable non-food biomass into petrochemicals, have developed a new catalyst that boosts the yield for five key “building blocks of the chemical industry” by a remarkable 40 percent over previous catalysts. This sustainable production process, which promises to be competitive and compatible with the current petroleum refinery infrastructure, has been tested and proven in a laboratory reactor, using wood as the feedstock.

“We think that today we can be economically competitive with crude oil production,” says research team leader George Huber, an Associate Professor in the Chemical Engineering Department.   

The news was published as an editor’s “Hot Paper” in the December 23 edition of the world’s most impactful chemistry journal, the German Chemical Society’s Angewandte Chemie. The groundbreaking article is entitled “Renewable Aromatics Production by Catalytic Fast Pyrolysis of Lignocellulosic Biomass with Bifunctional Ga/ZSM-5 Catalysts,” authored by chemical engineering graduate students Yu-Ting Cheng, Jungho Jae, and Jian Shi, Chemical Engineering Professor Wei Fan, and Huber.
 

“The big picture,” explains Cheng, “is that, starting with biomass and using our process, you can create all the same petrochemicals that are now produced with fossil fuels, but in a sustainable way that is also economical. And now we can produce a 40 percent higher yield of those petrochemicals.”

With the process carried out in Huber’s lab, his research team can take wood, grasses, or other renewable biomass and create five of the six petrochemicals that serve as the building blocks for the whole chemical industry: benzene, toluene, and xylene, which are aromatics; and ethylene and propylene, which are olefins. Methanol is the only one of those six key petrochemicals not produced in that same single-step reaction.

“The whole name of the game is yield,” says Huber. “What amount of aromatics and olefins can I make 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.”

The new production process could reduce or eliminate industry’s reliance on fossil fuels to make industrial chemicals worth an estimated $400 billion annually. The team’s catalytic fast pyrolysis technology has been licensed to New York City’s Anellotech, Inc., co-founded by Huber, which is scaling up the process to industrial size for introduction into the petrochemical industry.

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 thermally decomposes to form vapors. These biomass vapors then enter the team’s new gallium-zeolite (Ga-ZSM-5) catalyst, also inside the same reactor, which converts vapors into the desired aromatics and olefins. The economic advantages of the innovative process are threefold: All the reaction chemistry occurs in one single reactor; the process uses an inexpensive catalyst; and fungible aromatics and olefins are produced that fit easily into existing petrochemical infrastructures.

Each person on the research team had a specific role in the project. Professor Fan’s expertise is in catalyst synthesis, and he provided key insights into how to make the new catalyst, based on wedding the differing catalytic functions of gallium and zeolite. “Indeed,” Professor Fan explains, “this bifunctional Ga-ZSM-5 zeolite catalyst is an excellent example to show how we can design catalysts to improve the technique for converting biomass to biofuel by integrating different functional groups on the same catalyst. We believe there is still large room for the improvement of the catalyst which will further improve the performance of our catalytic fast pyrolysis process.”   

Using the information supplied by Professor Fan, Jae actually synthesized and characterized the new gallium-zeolite catalyst. Then Cheng tested the catalyst with model compounds as feedstock and showed the improved performance described in the Angewandte Chemie paper. Finally, Shi re-tested the process using wood as the feedstock.

Olefins and aromatics are the building blocks for a wide range of materials. 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.

“The ultimate significance of our research,” says Huber, “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 research reported in Angewandte Chemie uses the same catalytic fast pyrolysis reactor for turning biomass into aromatics and olefins that was described in the November 26, 2010, edition of Science, but with the added dimension of the new gallium-zeolite catalyst.

Using this new catalyst, how close is the catalytic fast pyrolysis technology to going commercial? “Close,” says Huber. (January 2012)