By Jan H. Schut
North American shale gas is reshaping petrochemicals. Two plenary speakers at the Society of Plastics Engineers’ International Polyolefins Conference 2013 in Houston, TX, in February describe some of the impacts. Tim Roberts, vice president at LyondellBasell (www.lyondellbasell.com) presents “Potential of Shale Gas for the Petrochemical Sector,” and Srivatsan Iyer, vice president of finance, planning, and strategy at Braskem (www.braskem.com) presents “North American Energy Transformation and Impact on Petrochemicals.” Videos of their plenary speeches are available to non-attendees for $50 (www.spe-stx.org/conference).
The big change for plastics processors is the first “on purpose” propylene plants in North America, which could make U.S. propylene the cheapest in the world. Here’s why: 90% of propylene is still made as a by-product of cracking for ethylene and gasoline. But the mixture fed to crackers in North America is changing with less naphtha from crude oil and more ethane from natural gas. In 2005, 30% of feedstock for cracking was naphtha and 70% ethane, according to research firm ICIS (www.icis.com) in Houston. By 2012 only 12% was naphtha and 88% ethane.
Ethane yields much less propylene, so the feedstock shift caused a 40% drop in U.S. propylene production from 13 billion pounds in 2005 to only 7.6 billion pounds in 2012. That 5.4 billion pound shortfall is driving a wave of new “on purpose” propylene plants. In the U.S. the feedstock will be propane. In China, the feedstock is refinery gas oil and methanol from coal. In Brazil, India, and elsewhere it’s waste biomass like sugar cane bagasse, wood scrap, and paper mill waste.
“ON PURPOSE” PROPYLENE FROM PROPANE
In the past year six new plants were announced in North America to make “on purpose” propylene from propane by a previously little used process called propane dehydrogenation (PDH). PDH removes two hydrogen atoms from propane (C3H8), converting it to propylene (C3H6). PDH chemistry isn’t new. The first plant was built in 1990 at National Petrochemical Co. in Thailand (now PTT Public Co.), a state-owned oil company, using the Oleflex process from Universal Oil Products, now UOP LLC (www.uop.com), part of Honeywell.
But PDH is a niche that only works where propane is cheap and propylene expensive. UOP has five more PDH units in Asia and four integrated with propylene production in Saudi Arabia at Advanced Petrochemicals Co. (www.advancedpetrochem.com), Al-Waha Petrochemicals Co., and Saudi Polyolefins Co. (www.tasnee.com) in Al-Jubail and at National Petrochemical Co. in Yanbu. Al-Waha and Saudi Polyolefins are joint ventures with LyondellBasell, which markets the propylene.
In the past the price of propylene and propane were so close in the U.S. that it wasn’t cost effective to dehydrogenate propane, but now with low cost propane from shale gas, it is. Petrologistics L.P. (www.petrologistics.com) in Houston started up the largest PDH plant in the world (544,000 metric tons/year) in 2010 and announced a second plant of the same size to start in 2017, both using Catofin PDH technology from Lummus Technology Inc., Houston, part of Chicago Bridge and Iron Co. (www.cbi.com).
Enterprise Products Partners L.P. (www.enterpriseproducts.com), Houston announced plans for a 750,000 metric ton/year PDH plant in Houston to start in late 2015, also using Lummus’s Catofin technology.
Dow Chemical Co. (www.dow.com), Midland, MI, announced plans for a 750,000 metric ton/year PDH plant in Freeport, Texas, to start in 2015 using UOP’s Oleflex PDH technology.
C3 Petrochemicals, an affiliate of Ascend Performance Materials LLC, a maker of polymer and fiber in Houston, requested permits for a new PDH plant at Ascend’s site in Chocolate Bayou to start in late 2015 using UOP’s PDH technology.
Taiwan-based Formosa Plastics Corp. U.S.A. (www.fpcusa.com), Livingston, NJ, announced plans for a 600,000 metric ton/year PDH plant in Point Comfort, Texas, to start in 2016. Sasol Ltd. (www.sasol.com) in South Africa is doing the feasibility study.
The Williams Companies Inc. (co.williams.com), Tulsa, OK, are planning Canada’s first PDH plant, a 500,000 metric ton/year plant in Redwater, Alberta, to start in 2018, using a PDH process designed by Fluor Corp. (www.fluor.com), Irving, TX.
“ON PURPOSE” PROPYLENE FROM GAS OIL AND METHANOL
Propane isn’t the only route to “on purpose” propylene. In China, dozens of new plants are being built to use gas oil and coal. Decades ago the Sinopec Research Institute of Petroleum Processing (www.ripp-sinopec.com) in Beijing invented a process called Deep Catalytic Cracking, using a zeolitic catalyst with gas oil in a conventional Fluid Catalytic Cracker, producing more propylene and less gasoline than conventional cracking.
There are seven Deep Catalytic Cracking plants currently operating or under construction in China, and one outside of China. Thailand Petrochemical Industries in Rayong, Thailand, started a Deep Catalytic Cracking plant in 1997, designed by Technip Stone & Webster Process Technology (www.technip.com), Stoughton, MA, with Sinopec’s process. Then Shaw Group Inc., Baton Rouge, LA, acquired recently by Chicago Bridge & Iron (www.cbi.com), had the exclusive license for Deep Catalytic Cracking outside of China and reportedly licensed 16 more plants. The Deep Catalytic Cracking license was sold to Technip last year.
More revolutionary are new technologies going from coal to olefins. At least 20 projects for coal-to-olefins or methanol-to-olefins have been reported in China. In 2010, Shenhua Group Corp. (www.shenhua group.com.cn) in Beijing, China, the large state-owned coal company, built the world’s first commercial coal-to-olefins plant at Shenhua Baotou in Inner Mongolia. The historic complex has a 1.7 million metric ton/year coal-to-methanol plant, followed by a 470,000 metric ton/year methanol-to-propylene plant and involved many international engineering partners.
Shenhua and GE Energy (www.ge-energy.com) partnered on the initial coal liquefaction and gasification technology to make syngas. Shenhua and GE also have a 50/50 joint venture since 2012 to develop and license clean liquefaction technology in China. The next stage at Baotou converts syngas (CO2 + H2) into methanol (CH3OH) using “MegaMethanol” technology from Lurgi GmbH (www.lurgi.com) in Frankfurt, Germany, which was recently acquired by Air Liquide in Paris.
Next comes the world’s first commercial methanol-to-propylene plant. This uses Lurgi’s new MTP technology with a multi-stage fixed bed reactor and steam dilution to convert methanol (CH3OH) selectively into propylene with gasoline as a by-product. Lurgi now has a second MTP plant operating at Datang International Power Generation Corp. (www.dtpower.com) in China , and a third under construction, also for Shenhua.
Other petrochemical companies have new methanol conversion technologies too. UOP and INEOS Group (www.ineos.com), formerly Norsk Hydro, developed an MTO (methanol-to-olefins) technology to convert methanol from coal into both propylene and ethylene, using SAPO-34 catalyst. They have sold three licenses in China: Wison (Nanjing) Clean Energy Co. Ltd. for 295,000 metric tons/year to start this year; Shandong Yangmei Hengtong Chemicals Co. Ltd for 295,000 metric tons/year to start in 2014; and Jiutai Energy (Zhungeer) Co. for 600,000 metric tons/year. UOP and Total Petrochemicals S.A. (www.totalpetrochemicals.com) in France have a demonstration MTO plant in Feluy, Belgium, since 2009.
Sasol Ltd. (www.sasol.com) in South Africa; KBR Inc. (formerly Kellogg Brown and Root) (www.kbr.com) in Houston; Axens S.A. (www.axens.com), Rueil-Malmaison, France, partnering with Headwaters Inc. (www.headwaters.com), South Jordan, UT; and SK Innovation Co. (eng.skinnovation.com) in South Korea also offer coal-to-liquids or methanol-to-olefins technologies and have recently built plants or announced licenses or co-licenses in China.
Chemical companies insist that “on purpose” propylene will have to meet the same purity specs as conventional polymer grade monomer. But “on purpose” propylene is made with different feedstocks, different catalysts, and more difficult chemistries. PDH units use propane, which is typically cleaner than naphtha, so propylene from PDH shouldn’t have purity issues. Coal-based olefin processes, however, are new and start with liquefied coal, which has impurities like mercury, arsine, and sulfur. These impurities have to be removed before it’s made into syngas, or they hurt the catalyst in the next methanol reaction. So propylene from gasified coal is more problematic.
The Holy Grail for chemists would be a reaction that goes directly from methane (CH4), the main component of natural gas and the least expensive hydrocarbon, to ethylene for olefins and gasoline. Siluria Technologies Inc. (www.siluria.com), San Francisco, CA, a silicon-valley energy startup, recently announced a patent-applied-for catalyst for “oxidative coupling of methane to ethylene” (U.S. Pat. Applic. # 20120041246 and 20130023709). Siluria used molecular biology to design the catalyst in which a virus is coated with metals to make something like a tangled ball of nano wires. It’s a catalyst approach that has been tried before, but not commercially. This year Siluria plans to start building a demo plant for 1000 pounds/day of ethane. Dow, BP p.l.c. (www.bp.com), and other chemical companies also hold patents on catalysts for methane conversion to olefins, but nothing has been commercialized.
“ON PURPOSE” PROPYLENE FROM BIOMASS
New plants and processes are also in R&D using heat, fermentation, and metathesis to make propylene from biomass, but several projects are either on hold or changing to natural gas-based feedstock. Braskem S.A. (www.braskem.com) in Sao Paolo, Brazil, announced plans in 2010 to build a semi-works 30,000 metric ton/year metathesis plant in Rio Grande do Sul, Brazil, to start up this year. But the plant is delayed because of market conditions, Braskem says.
Metathesis is a difficult chemical reaction that rearranges molecules and is much more complicated than simple cracking of hydrocarbons. Bio-ethylene (C2H4) is first dimerized, or combined in pairs, into bio-butene (C4H8). Then metathesis rearranges the bio-butene (C4H8) and bio-ethylene (C2H4) into bio-propylene (C3H6).
Propylene metathesis was invented by Philips Petroleum Co. in the early ‘60s and used by Shell (the SHOP or Shell Higher Olefin Process) and Lyondell in the ‘80s to make propylene from butene. Lummus bought the rights to Phillips’ metathesis process and uses it in Lummus’s OCT (olefins conversion technology) to make propylene and ethylene.
A Dow/Mitsui Chemical joint venture in Brazil was announced last year to make bio-ethanol from sugar cane into bio-polyethylene, but this venture is also on hold. Dow planned to use dehydration, not metathesis.
Plasma is another potential route to propylene. High temperature plasma is used to gasify biomass, including municipal solid waste and even sewage. Zeus Development Corp., a research firm in Houston, lists hundreds of such gasification projects globally (www.zeusintel.com/Gasification/GlobalGasificationProjectListing.aspx). It’s fascinating reading, but most projects are for power, not plastic.
A few gasification projects, however, have plastic potential. Alter NRG Corp. (www.alternrg.com) in Calgary, Alberta , which owns Westinghouse Plasma, started up a very high temperature (2500 °C) Westinghouse Plasma gasifier at Wuhan Kaidi Holding Investment Co. (www.kaidi-hi.com/en) in Wuhan, China, to convert 100 tons/day of waste biomass into syngas, which could be converted into methanol and then olefins.
Coskata Inc. (www.coskata.com), Warrenville, IL, a biofuel startup, partnered with Total and IFP Energies Nouvelles (www.ifpenergiesnouvelles.com) in France and ran two years of tests with Westinghouse’s plasma technology to gasify wood waste into syngas and reform natural gas to feed fermentation for biofuels and bioplastics. Coskata shelved IPO plans last year and switched from biofeedstock to natural gas.
Using low temperature plasma, TopLine Energy Systems Inc., Brookville, FL, announced a partnership last year with Maverick Biofuels Inc. (www.maverickbiofuels.com), Research Triangle Park, NC, to integrate TopLine’s PRISM plasma reactor for syngas with Maverick’s chemical process to convert waste biomass into olefins and then into alcohols for biofuel. The bio-olefins could also be used for bioplastics.
Envergent Technologies LLC (www.envergenttech.com), part of Honeywell, a joint venture of UOP (also part of Honeywell) and Ensyn Corp. (www.ensyn.com) in Wilmington, DE, uses pyrolysis to convert forest and agricultural waste into syngas. Envergent has sold one license in Malaysia, but it’s for energy, not plastics.
There is even, in R&D, a direct bio-route to propylene. Global Bioenergies (www.global-bioenergies.com) in Evry, France, last October claimed to have proven the first process for direct conversion of biomass into propylene by fermentation. The patent-applied-for technology (U.S. Pat. Applic. # 2011165644) uses genetically modified micro-organisms to convert glucose into propylene. But the problem is still cost versus gas.