--Analysis of Aromatic Hydrocarbon Technology Routes (Part 2)

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--Analysis of Aromatic Hydrocarbons Production Routes (Part 2) Author/Source: Date: 2016-08-26 Clicks: 8 To fill the gap in the aromatic hydrocarbons market, the industry has turned its attention from oil-based routes to coal-based routes, as well as to biomass-based routes. The technology roadmap for key areas outlined in \"Made in China 2025\" explicitly calls for making significant progress in the field of bio-based aromatic hydrocarbon synthesis. At the 2016 China Aromatic Hydrocarbon Industry Development Conference, which concluded in mid-August, experts present highly endorsed the approach of using biomass to produce aromatic hydrocarbons. But when it comes to the future, their attitude can be summed up in one sentence: the road is long and arduous, but those who keep moving will eventually reach their destination. Domestically: New technologies are just emerging. “The household waste and straw generated in our country each year have the potential to produce 170 million tons of gasoline, diesel, and aromatics per year.” ”Professor Wang Hualin from East China University of Science and Technology outlined the prospects of biological routes to aromatics. This figure of his is not unfounded; it is based on a novel process route for aromatic compounds using biomass as raw material, which is a technical approach that combines petroleum refining with chemical and biochemical processes. Specifically, this route uses waste straw and mineralized household waste in combination to produce gasoline, diesel, and aromatics. So-called mineralized household waste refers to waste that has become solidified after being buried underground for many years. According to Wang Hualin, 6 tons of straw can be used to produce 1 ton of gasoline, diesel, and aromatics. China produces over 700 million tons of straw annually, which means there is a potential supply of over 100 million tons of gasoline, diesel, and aromatics. At the same time, China generates about 300 million tons of urban waste each year, of which approximately 70 million tons contain gasoline, diesel, and aromatics. It is a great coincidence that the distribution of municipal solid waste in our country closely matches that of oil refineries, which makes it possible to implement a technical approach that combines oil refining with chemical and biochemical processes. “The process concept for producing gasoline, diesel, and aromatics through straw pyrolysis and hydrogenation involves using straw and household waste; through molecular tailoring and directed conversion, the lignin is hydrogenated and deoxygenated to produce aromatics, while cellulose and hemicellulose are hydrogenated and deoxygenated to yield gasoline and diesel feedstocks. ”Wang Hualin said. Following this approach, researchers developed two types of devices. One is a pyrolysis and hydrogenation device that converts straw into raw materials for the production of gasoline, diesel, and aromatics; a rapid pyrolysis pilot plant with a capacity of 3 tons per hour has already been built, and this device is similar to the catalytic cracking units used in the petroleum refining and chemical industries ； Another is a pilot-scale unit for boiling-bed hydrodeoxygenation and fixed-bed hydrogenation refining, with a capacity of 1 liter per hour, built by an enterprise in Henan. Pilot test results show that the components of biomass pyrolysis oil (wood tar) include alkanes, aromatics, olefins, phenol, etc. After hydrogenation to improve its quality, the components of the hydrogenated oil are 46.44% aromatics, 35.09% alkanes, and 8.56% phenol. Further processing via blending can yield aromatics, while hydrocracking can produce gasoline and diesel. Industry experts say that, overall, the research and development of biomass-based aromatic hydrocarbon production processes in China is still in its initial stages. Abroad: Industrialization is on the way. Compared to domestic markets, there are more companies abroad that are involved in research and development as well as industrialization, and such research and development activities began earlier there. According to the reporter’s understanding, some biomass-based aromatic hydrocarbon production technologies developed by foreign companies have already achieved small-scale commercial production. The progress made by the University of Massachusetts in the United States regarding a one-step process for producing aromatic compounds from cellulose biomass has attracted significant attention within the industry. They developed a process for converting biomass into aromatics and founded Anellotech to bring it to industrial production. This technology is based on a catalytic rapid thermal cracking process, which rapidly heats biomass in a fluidized bed reactor to produce oxides, which are then converted into chemical-grade aromatics using specialized zeolite catalysts. Compared to traditional processes that use petroleum as a raw material to produce aromatics, this technology has lower costs. In January of this year, Anellotech implemented industrialization of this technology. According to their calculations, this technology has a cost advantage when oil prices are above $60 per barrel. The industry generally believes that, among the existing routes for producing bio-aromatics, Anellotech’s process of producing aromatics through biomass pyrolysis is the one with the best cost and economic efficiency. The BioForming process, developed by the U.S.-based company Virent in collaboration with the University of Wisconsin-Madison, offers significant investment advantages due to its ability to be implemented through modifications to existing refining facilities. Using sugar as a raw material, this process combines the hydrolysis of plant fibers with traditional catalytic hydrogenation techniques to produce mixed aromatic hydrocarbons containing benzene, toluene, and xylene from plant-based sugars, which can then be further processed into p-xylene. The advantage of this process is that by combining liquid-phase reforming (APR) technology with traditional catalytic hydrogenation and condensation techniques, the reaction units can be modified using existing refining facilities, with an investment cost of only 1.75 to 3 dollars per gallon of product ； The by-produced olefins can serve both as by-products and for powering the facility, offering good process economics. Unlike the direct conversion of biomass into aromatics, in recent years some manufacturers have taken a different approach: they first use established processes to convert biomass into organic chemicals with lower added value, and then transform these bio-based chemicals into aromatics with higher added value. Among them, the GIFT process developed by the American company Gevo, which uses renewable raw materials to ferment and produce alcohols, is the most representative. The GIFT process first converts biomass feedstock into isobutanol, which is then converted into isobutylene through a dehydrogenation reaction; the conversion rate of isobutanol in this process exceeds 99% ； The resulting isobutylene becomes C8 olefins in the polymerization reactor ； C8 olefins are converted into PX products through dehydrocyclization, achieving a PX selectivity of over 75% and a purity of 99%. Gevo has collaborated with Japan’s Toray Industries to build an industrial-scale facility. The greatest advantage of this process is the direct production of high-purity PX under mild conditions, eliminating complex processes such as isomerization and aromatic separation, resulting in a relatively simple production process. Bottlenecks: raw materials, catalysts, reactors. According to interviews with journalists, looking at the research and development efforts related to the production of aromatics from biomass both domestically and internationally, although the prospects are promising and significant progress has been made, the majority of these approaches are still in the development stage. Even though some have achieved small-scale industrial production, there is still a significant gap in terms of economies of scale compared to the traditional oil route, and many potential problems remain that need to be addressed urgently. Firstly, a stable supply of biomass raw materials has always been a challenge in the development of biochemical industry, and the same is true for bioaromatics. Biomass raw materials are abundant but scattered, and their composition is complex. To scale up the production of aromatics using biological processes, there must be a sufficient and stable supply of raw materials. Given the current level of agricultural production in China, resolving this issue requires coordinated efforts from various parties to find a reasonable and feasible approach. Secondly, for many biomass-based processes for producing aromatics, the catalysts and reactors used in thermal cracking and hydrolysis processes also represent challenges. At the meeting, some representatives told reporters that although they are interested in using biomass to produce aromatics, the conversion rates and product purity of existing processes are low, making it difficult for them to compete with the petroleum-based approach. To improve these two indicators, progress is needed in the development of corresponding catalysts and reactors. However, some experts believe that combining biochemical engineering with traditional refining and chemical manufacturing, as done by East China University of Science and Technology, is also a good approach. It is worth paying attention to the use of existing pyrolysis units, with biomass resources as raw materials, to partially replace fossil resources in the production of aromatics.