Catalytic Chemistry - novel processes to produce hydrocarbon biofuels

A number of novel pathways are being developed for producing advanced biofuels, via catalytic chemistry. The aim is to produce petrochemical replacements - synthetic fuels that can be used in conventional engines ('Drop-in' biofuels). Advanced catalytic pyrolysis is covered by the page on bio-oil and biocrude.

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Chemical Catalysis

In February 2012, Shell announced the construction of an advanced biofuels pilot plant at the Westhollow Technology Center in Houston, USA, which will produce drop-in biofuels using a thermo-catalytic process technology licensed from its commercial partner Virent.

Previously, in March 2010, Virent and Shell announced the world's first biogasoline demonstration plant based on Virent’s BioForming® process. The demonstration plant in Madison, WI can produce up to 38,000 litres (10,000 U.S. gallons) per year, which will be used for engine and fleet testing. In June 2010, Virent announced that it has secured $46.4m from Cargill and Shell to accelerate biofuel scale-up.

Virent’s BioForming® process can convert a wide range of feedstocks, including non-food and home grown energy sources, into the variety of fuels and chemicals now made from fossil fuels. The BioForming® process, is based on the novel combination of Virent’s core APR technology with conventional catalytic processing technologies such as catalytic hydrotreating and catalytic condensation processes, including ZSM-5 acid condensation, base catalyzed condensation, acid catalyzed dehydration, and alkylation. Like a conventional petroleum refinery, each of these process steps in the BioForming platform can be optimized and modified to produce a particular slate of desired hydrocarbon products. For example, a gasoline product can be produced using a zeolite (ZSM-5) based process, jet fuel and diesel can be produced using a base catalyzed condensation route, and a high octane fuel can be produced using a dehydration/oligomerization route.

(Source: www.virent.com)

In the Netherlands, Avantium Furanics are developing processes - proprietary "YXY" technology - that use catalytic dehydration/esterification of carbohydrates (e.g. cellulose, hemi-cellulose, starch and sucrose) to produce furan derivatives that can substitute hydrocarbons deived from petroluem. These furanic building blocks may be used to create biofuels, biopolymers and other products. The process also yields heat and power. Avantium is currently focused on production of PEF (Polyethylene furanoate) from FDCA (furan-dicarboxylic acid), but is also developing the use of furanics as advanced biofuels. The company successfully conducted a range of engine tests using blends of diesel and Furanics (in different ratios), as well as blends of gasoline and Furanics. Avantium has since collaborated with DAF Trucks and Volkswagen for more extensive engine testing programmes.

The 50M Euro CatchBio project (Catalysis for Sustainable Chemicals from Biomass) involves public-private partnership R&D on use of chemical catalysis on biomass feedstocks (2008-2015) to produce advanced biofuels and novel biochemicals.

In the US, Midori Renewables developed a patented reusable solid catalyst to convert cellulosic biomass into sugars.

In March 2014, Oak Ridge National Laboratory (ORNL) announced that Vertimass LLC, a California-based start-up company, had licensed an ORNL technology that directly converts ethanol into a hydrocarbon blend-stock for use in transportation fuels, using an inexpensive zeolite catalyst. This overcomes the ethanol blend wall. The drop-in blend-stock can be used in to convert ethanol into hydrocarbons for blending with gasoline, diesel and jet fuels

In October 2015, Vertimass LLC announced the completion of the technology validation that verifies the benchmark performance, initial process design and preliminary cost information for a new award of $2 million by the U.S. Department of Energy’s Bioenergy Technology Office. This will enable Vertimass to build the foundation from which to begin scale of its technology within two years.

Aqueous phase hydrodeoxygenation (APHDO) using solid heterogeneous catalysts to convert aqueous carbohydrate solution into targeted gasoline range products or chemicals, has been developed at the Huber Biofuels Research Group, University of Wisconsin.

Production of HMF, DMF, Levulinic acid, GVL gamma-valerolactone via Catalysis

Researchers at the University of Wisconsin, Madison, have been researching the conversion of cellulosic materials to 5-hydroxymethylfurfural (HMF), which can then be converted to alkenes (building blocks for synthetic fuels). The process requires expensive ketones and also produces levulinic acid and formic acid. Less costly catalysts can be used to convert these acids into gamma-valerolactone (GVL). GVL can be catalysed into butene, which is readily converted into transport fuels, with an overall efficiency of 95% (GVL -> fuel). Research is now focused on finding a highly efficient route from cellulose to GVL.

In September 2014, Colorado State University published its technology marketing strategy Catalytic Conversion of Biomass-derived Feedstock (HMF) into Value Added Chemicals and Biofuels. This describes the catalytic reaction system by which the biomass-derived feedstock chemical HMF can be upgraded into a higher carbon content intermediate compound. Further processing steps can convert the intermediate into jet and diesel fuels or into value added specialty compounds.

Hydroxymethylfurfural can be converted to 2,5-Dimethylfuran (DMF) which has potential for use as biofuel. In June 2012, researchers at University of Delhi published "A Catalytic Method of Rapid DMF Biofuel Synthesis" in The Berkley Energy Review. See also DMF - A New Biofuel Candidate published by Guohong Tian, Ritchie Daniel and Hongming Xu University of Birmingham and Newcastle University, UK. [Ref: Biofuel Production- Recent Developments and Prospects, Dr. Marco Aurelio Dos Santos Bernardes (Ed.), ISBN: 978-953-307-478-8, InTech].

The EC FP7 project DIBANET is developing the production and use of levulinic acid to make diesel miscible fuels sustainably (via esterification of ethanol with levulinic acid over solid acid catalysts). Further information is available in the latest DIBANET Newsletter. The project aslo offers an elearning portal covering hydrolysis and thermal processing topics related to the project.

Techniques for production of levulinic acid as 'biogasoline' are also being developed by University of California at Davis.

KU Leuven, Centre for Surface Chemistry and Catalysis, Netherlands, has developed a chemical catalytic process for converting sawdust into saturated hydrocarbon chains (HMF). See Direct catalytic conversion of cellulose to liquid straight-chain alkanes, Energy & Environmental Science, September 2014. The catalytic reaction proceeds at elevated temperatures under hydrogen pressure in the presence of tungstosilicic acid, dissolved in the aqueous phase, and modified Ru/C, suspended in the organic phase. Tungstosilicic acid is primarily responsible for cellulose hydrolysis and dehydration steps, while the modified Ru/C selectively hydrogenates intermediates en route to the liquid alkanes.

Researchers at the University of Science and Technology of China have developed a new catalytic route for the conversion of biomass carbohydrates into gamma-valerolactone (GVL) without using an external H₂ supply. A model experiment with glucose provided gamma-valerolactone in 48% yield. [Source: Angewandte Chemie International Edition Vol 48, Iss 35, 6529-6532, 23/07/09]

Shell has also reportedly tested blends of ethyl valerate (EV) derived via hydrogenation of gamma-valerolactone (GVL) into valeric acid followed by esterification. "Petrol blended with 10-20% EV would largely meet European petrol specificiations (EN 228). EV also leads to an increase in octane rate (RON and MON) of the fuel, without affecting other characteristics, such as corrosion and plaque formation. The fuel density and oxygen levels also increase. EV also reduces the volatility and levels of aromates, olefines and sulphur." [Source GAVE]

From 2007 Maine Bioproducts operated a pilot plant in Gorham, Maine to demonstrate the Biofine process, which involves high-temperature dilute-acid-catalyzed hydrolytic breakdown of cellulose to form levulinic acid.