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Catalysts are Key

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Catalysts are Key

February 28, 2013 - 19:00
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The elusive goal of a refinery with biomass as a feedstock has moved a step closer to reality, thanks to technology developed by the Gas Technology Institute (GTI) of Des Plaines, IL,and Houston-based Catalytic Research Institute (CRI).

The IH2 technology makes use of proprietary catalysts developed through the cooperative ef- forts of CRI’s affiliates in their research facilities in Bangalore, India, and manufactured by CRI affiliates in the US, Belgium and Germany.

Chicago-based GTI is a non-profit body that was originally established by a consortium of gas companies. Its current mandate is to develop energy solutions, typically working with a third party. It has a staff of 250 and holds more than 1,200 patents.

GTI and CRI have commercial agreements in place for joint development and novel R&D focused on catalyst development, and an exclusive worldwide license granted to CRI as the sole licensor of IH2 technology.

CRI’s involvement with GTI began three years ago. Mike Demaline, Global Business Manager for Renewable Fuels in the Forestry, Pulp & Paper sector explains, “We got involved because GTI knew they needed catalysts to develop the tech- nology. As we familiarized ourselves with their process, we knew it had the potential to trans- form the industry by providing transportation fuel range hydrocarbons direct from biomass. We supplied the initial catalysts that GTI used and we knew we could significantly enhance the process by further developing proprietary catalyst lines.”

With an eye on both sustainability and the bottom line, CRI realized agreements between the two organizations relative to IH2 technology made perfect sense.

How about seaweed?

IH2 is a catalytic thermo-chemical process designed to produce fungible liquid transportation fuels and/or blend stocks from ligno- cellulosic and other forms of biomass. Wood was GTI’s initial choice because it knew the material and already had a concept in mind. Perhaps more importantly an abundant, sus- tainable supply could be readily available at a good price. However, the IH2 process has been shown effective at the conversion of a broad range of other biomass types includingseaweed, aquatic plants, algae, bagasse, corn stover and even municipal solid waste. Future work will examine customer specific feedstocks including miscanthus, jatropha and residues from sweet sorghum.

The feedstocks are fungible, meaning that the molecular structures present are the same as those in fossil-based fuels such as gasoline, jet fuel or diesel. Demaline says that at first, he expects the renewable hydrocarbons will be blended with traditional fuels. Independent life cycles studies suggest that the carbon footprint should be at least 94% lower than traditional fossil hydrocarbons on a seed to wheel basis.

The development of alternative fuels is im- portant to the US as the government encourages the use of non-fossil based fuels. However, the US consumes 13.5 million barrels per day of liquid transport fuel , making goals non-fossil based fuels challenging to meet.

This may be evidenced by standards which originally set goals of 36 billion gal/yr of renew- able fuel, which have been amended more recently to 25.7 billion gal/yr.

A paper co-authored by GTI and CRI personnel shows possible scenarios of the IH2 process using various feedstocks. For example, it shows a 2,000-bone-dry-ton wood feed/day plant could use stumps, branches, sawdust, bark and even the possibility to blend in various mill sludges. Hardwood or softwood, it makes no difference.

Research shows the IH2 process can produce up to 92 gallons of liquid fuel per ton of wood feedstock (on a dry, ash-free basis). This totals 184,000 gal/day. The gasoline:diesel ratio would be expected to be 70:30.

It is a low-waste producing process. Product oxygen is below detectable limits and the total acid number or TAN is less than 0.03. Demaline points out this is very low and that most refineries invoke special procedures when processing crude oil with a TAN of more than two. Tradi- tional pyrolysis oils have a TAN in excess of 100.

Still, to put it into perspective, to meet the amended fuel blend requirements of the US would potentially mean 400 such “bio-refineries” would needed by 2020 .

Demaline stresses that CRI and GTI are poised to meet the relevant challenges in the deployment phase. It will not be easy, since in full production, a 2,000-ton/day plant in a day would produce the equivalent of 12 hours’ production of a world-scale fossil fuel refinery.

Moving ahead, Demaline states “We can make a dent in these numbers. The market is big because of the mandate.”

“Game changing” technology

So how does it work? Demaline says the IH2 process is “game changing”. The process equipment is not new or novel nor does it require special materials to construct. It can be refinery or mill integrated although the refinery integration model may have better economics.

Lignocellulosic biomass contains oxygen and this must be removed for it to become a hydrocarbon; that’s why the catalytic thermochemical process is used. Breaking the carbon-oxygen bonds and replacing them with carbon-hydrogen bonds (and forming water as a result) creates heat (i.e. it is exothermic) that, for example, can be used to make high pressure steam for a paper machine dryer.

The oxygen from the biomass is removed primarily as water. The water is then used to- gether with light gases produced by the process as the input to create all the hydrogen the system needs together with CO2. The CO2 is referred to as “green” CO2 because it comes from a non-fossil source. Demaline says this CO may be captured to create a product for enhanced oil recovery, food or chemical products. The oxygen from the biomass is removed primarily as water. The water is then used together with light gases produced by the process as the input to create all the hydrogen the system needs together with CO2. The CO2 is referred to as “green” CO2 because it comes from a non-fossil source. Demaline says this CO may be captured to create a product for enhanced oil recovery, food or chemical products.

The cellulose and lignin molecules are turned into gasoline, jet fuel and diesel molecules. To get to the end product, there are various stages. The first is feed conditioning where the raw material is sized (2-4 mm is optimum), mixed and dried.

The first stage reactor is a bubbling fluidized bed (BFB) but unlike a traditional BFB boiler, no sand is used. “Instead, we use advanced proprietary catalysts,” Demaline explains. The BFB is loaded with the catalyst, which acts as a heat transfer mechanism.

Inside the BFB, the biomass meets the catalyst in the presence of a low-pressure hydrogen atmosphere. Hydrogen is produced in a hydrogen manufacturing unit (HMU).

The reaction takes seconds in the pressurized reactor. By the end of the first stage, the material is in vapor form and the vapor includeshydrocarbon molecules of varying length as well as the water.

The first stage takes out the majority of the oxygen. The second stage takes out the rest as well as undesirable trace elements such as sulfur and nitrogen.

A cyclone collects char and ash (about 10-12%), the char having an energy content of 11,000-12,000 BTU/lb.

The process requires a fossil fuel source such as natural gas only at startup. It is used in three places: to heat the first stage reactor; to pre-heat the feed to the second stage reactor and as an initial feed gas in the HMU. The process is self-sufficient and self-sustaining after startup, no longer requiring the need for natural gas addition.

Demaline says there are various things to look at when considering a feedstock. Elemen- tal analysis provides a hydrogen to carbon atomic ratio which correlates with both the liquid fuel yield and liquid fuel quality; a higher ratio predicts better yields and fuel properties. For example, the H/C ratio for wood is 1.4, equal to or lower than other feedstocks studied such as micro algae (1.7), macro algae (1.6), lemna (1.5), corn stover (1.5) and bagasse (1.4).

With wood as the feedstock, yield of the liquid hydrocarbon is 28 wt% using the current generation of catalysts. With each new genera- tion, yield is expected to increase. Also, the boiling point curve can be moved, which allows one to shift the ratio of the product one produces, e.g, more gasoline or more diesel.

Demaline explains that a refinery takes crude oil and separates it by boiling point, a process known as distillation or fractionation. Successively heavier products are collected by boiling at higher temperatures, the liquids are then produced by condensing the vapors it to get the various products. The boiling points increase as one goes from gasoline to jet fuel and then finally diesel .

Catalysts are the key to translating distillation and fractionation into a biorefinery, Demaline states. The pilot plant at GTI is now running a third generation catalyst while work on the fourth generation is underway at the Bangalore laboratory. Demaline says one benefit of the fourth generation catalyst will be to increase the diesel yield and cetane. Cetane is to diesel what octane is to gasoline; the more cetane, the higher the performance.

Diesel engines are currently more popular than gasoline everywhere outside of the US. Demaline points out that increasingly stringent reg- ulations expected from the US government concerning greenhouse gas (GHG) emissions, could push US auto manufacturers to increase mileage per gallon, through all means that they may have at their disposal, with a key one being diesel engines in passenger automobiles, which is already becoming more popular in North America.

“We hope to get to a point where someone comes up with a feedstock and says they want to produce only diesel so then we would develop a catalyst system to do just that,” Demaline adds. “We have standard catalysts which are versatile for multiple feeds and then we have custom catalysts designed for specific types of feedstock and products desired.”

Pilot results encouraging

Work started in a laboratory-scale unit at GTI. All the products emerged together and were then distilled and used for a feedstock qualification.

In September 2011, an automated 50-kg feed/day continuous pilot plant output was achieved at GTI.

The pilot plant is being used to confirm earlier yield estimates at smaller scale and confirm catalyst life. Thus far, Demaline says that all concerned are very pleased with the pilot plant’s performance, which has been in continuous operation since March 2012.

The pilot plant also allows CRI to produce fuels in sufficient quantity to start fuel qualification. The US Environmental Protection Agency has to look at the product as it relates to various standards, such as ASTM as well as the European equivalents. The toughest specification is for jet fuel. Demaline says the process can take three to six months.

What will all this cost? In the US, the National Renewable Energy Laboratory (NREL) is involved with estimating process economics from a broad spectrum of biomass processes under similar economic conditions. NREL examined a 2,000-ton/day design of wood (received at 50% moisture dried in situ to 10%). The plant design takes the hot flue gases from the HMU to dry the incoming biomass, which frees all the heat generated by the process to go back to, for example, the paper machine.

Using a “greenfield” site, total installed equipment (TIC) cost was estimated at the time of the study to be US$112 million of which the HMU is the most expensive single piece at approximately 45% of the total.

Total capital investment (TCI) was estimated to be $232.8 million. In 2012 dollars, minimum sales price to provide overall IRR of 10% on top of 60% financed at 8% was calculated to be $1.76/ gal with wood at $71.97 per dry ton. Feedstock accounted for 55% of the operating cost.

To achieve a 10% IRR on a $232.8-million investment, Demaline says the study suggested a company would need a selling price of $1.76/ gal. If the unit was integrated with a refinery and did not need to purchase the HMU, using refinery hydrogen instead, a selling price of $1.49/gal would be needed to achieve 10% IRR.

He says that a pulp and paper company might be positioned to spend less than the full $232.8 million, and might be able to reduce costs to as low as $112 million. Demaline adds that these numbers have no subsidies attached, but some are available in the current market . He also points out that the reformulated blendstock for oxygenate blending (RBOB), i.e., gasoline, has been running about $3/gal in recent months.

Look to Europe

Demaline says a pulp and paper producer would under the current business model buy a license from CRI for the technology (based on annual design production) and a fee for the engineering design. That firm could own and operate the plant or perhaps enter into a joint venture with another pulp and paper producer or even a refinery. CRI started talking with pulp and paper producers about 24 months ago .

Actually, the first interest in joint ventures came from some refineries. “They don’t know how to source, handle or treat the biomass, but they can do the rest, which a pulp and paper producer can’t,” Demaline explains. But, to be cost effective, the biomass should be available within a 75- to 100-mile radius.

One excellent model, Demaline says, could be a site where a mill has shut one or two large paper machines. This would mean that the wood supply is available. Another model mightinvolve a company that may want to reconfig- ure a mill site that has been mothballed. “We would not go to a world-scale mill and ask to colocate unless the owner knew the feedstock was available. We will always defer to the biomass owner because they know what’s available.”

Scales up to 2,000 dry tons feed/day are possible as single trains. For wood, a company must look for sources greater than 500 tons per day to be economic, the larger the better. “When we talk with a producer, we ask what they can sustainably provide as a feedstock,” Demaline says. “We’ve been told from 500 to 1,500 tons/ day on a co-location basis, i.e., a brownfield site.” The 2,000-ton/day model cited previously refers to a greenfield site.

Demaline believes the first commercial scale plant fed by wood might be built outside of North America. “It will take the one at commercial scale and then you’ll see many. The first will be in a mature market with good access to feedstock.”

In summary, Demaline says it is important to remember that the IH2 technology provides more than high quality transportation fuel range renewable hydrocarbons, but also renewable CO2, high-pressure steam/power, char ( which can be combusted to recover more energy), and water that can be sent back to the HMU. The process produces little waste and all of the hydrogen needed in the process can be self-generated from the incoming biomass.

Demaline says other benefits that distin- guish IH2 from other biorefinery processes include: feedstock flexibility; attractive economics (low capex and operating expenses); both stages are exothermic; it integrates existing technology; fungible high-purity hydrocarbon products made that replace the “whole barrel”, i.e. the products are not specific to one fuel.

In the near future, CRI is expecting completion of a contracts for front end engineer- ing and design for a 5-ton/day demonstration plant. And, work is about to start on the design for commercial-scale plants of 500 and 1,000 tons/day. A commercial-scale reactor would be about 65 ft high and 9 ft in diameter. The num- bers should be in by 1Q 2013 and Demaline hopes basic engineering on the first site would begin early in 2014. The plan is for the first commercial-scale site using IH2 technology to begin in early to mid 2016.