China Seeks To Modernize Its Petrochemical Technology

I SCIENCE/TECHNOLOGY

China Seeks To Modernize Its Petrochemical Technology • Current efforts to bring domestic chemical industry up to international standards technologically are starting to bear fruit Joseph Haggin, C&EN Chicago hinese chemical arts and sciences have a long history. The history of chemical technology in China, on the other hand, is shorter, and much of the country's current effort in this area is aimed at bringing the domestic chemical industry "up to speed." Although that industry has been handicapped by institutional problems, a high level of native talent and endless hard work are nevertheless gradually pulling the industry into the modern era of international competition. Much has been made of the Chinese invention of paper, gunpowder, and other practical products of the chemical arts. Indeed, at one time China was a leading world technical power. But

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China also went into a technical, economic, and political decline, more or less coincident with the rise of the colonial powers and the internal disintegration of the empire. How much mutual influence these historical events exerted will continue to be a subject for debate. What isn't debatable is that China today has established major materials and chemical industries, placing the country among the leaders in oil, gas, and chemical production. Since the incorporation of China Petro-Chemical Corp. (Sinopec) in 1983, the development of the petrochemical industry has accelerated, suggesting that Chinese chemical technology has come of age (see page 9). Much of the present chemical industry was built on the base of imported technology and equipment. The trauma inflicted on professional groups by the Great Leap Forward in the late 1950s and the Cultural Revolution in 1966 did little to advance the chemical industry. It has been repeatedly noted that professional development probably lost one, and maybe two, generations of practitioners from those two

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FEBRUARY 24,1992 C&EN

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events alone. But that handicap didn't prevent the establishment of the modern Chinese chemical industry, which has a de facto birth date about the beginning of 1980. One characteristic of the Chinese petrochemical industry is its relatively high degree of vertical integration, which reflects central control by the state. In principle, vertically integrated corporations are supposed to benefit by minimizing charges from internal transfers. However, verticality does tend to stratify an organization and sometimes eliminates healthy divisional competition. The Chinese petrochemical industry is segregated into manufacturing complexes, each with its own educational institutes and research and design groups. Although administration of the entire enterprise may be centrally controlled, each manufacturing unit is, effectively, an autonomous unit that fills a niche rather than competes for markets. Despite all the problems, the Chinese petrochemical industry is modernizing and expanding, generating new cadres of greater professional competence along the way. Periodically the fruits of its labors are encountered in conferences such as the International Conference on Petroleum Refining & Petrochemical Processing (Interpec China 91), which7 was held in Beijing last September. Sinopec's largest single petrochemical unit is claimed to be Yanshan Petrochemical Corp. in the southwest suburbs of Beijing. It is built around a crude-oil refinery that started operations in 1969. The refinery was begun with, and has continued to rely on, imported technology, especially since 1980. Its main products are gasoline; diesel oil; benzene, toluene, and xylene; heavy oil; and petrochemical raw materials. Included in the basic refinery scheme is a hydrogen fluoride alkylation unit licensed from Phillips Petroleum.

Downstream are three chemical works and three plants—a synthetic rubber plant, a polyester plant, and a chemical fiber plant—with associated departments for engineering, construction, and sales. The first chemical works operates almost entirely with imported technology, including an ethylene plant licensed from Lummus Inc., a low-density polyethylene unit from Sumitomo, an ethylene glycol/ ethylene oxide plant from Scientific Design Co., a benzene plant from Houdry, a p-xylene plant from UOP, a styrene plant from Monsanto, and a polystyrene plant from Dow Chemical. The second chemical works produces phenol, acetone, polypropylene, glass-reinforced polypropylene, and polystyrene, using imported technology. Among the licensors are Mitsui, Fibril, and Bruckner. The third chemical works produces heavy alkyl benzene, synthetic lube oil, m-cresol, and related products. The main product of the rubber plant is ds-1,4-polybutadi-

ene rubber made from a Chinese process. The polyester plant produces mainly polyester chips. The chemical fiber plant was totally imported as trade compensation in 1973. The products of this plant are tufted and woven carpet materials. The research institute includes at least three commercial plants and numerous pilot plants. Research has concentrated on organic synthesis, high molecular weight materials, and catalysts, in addition to the usual varieties of projects on environmental improvement, safety, corrosion prevention, and the like. A major achievement of the institute has been development of a styrene-butadiene-styrene block-copolymer process that has been commercialized. Recently, the process was licensed to Italy's EniChem. The institute also develops catalysts for internal use and potential license. A smaller but more diversified complex is the Qilu Petrochemical Corp. in provincial Shandong. There, chlorine/

caustic production and fertilizer production have been added to the usual mix of petrochemicals. In some respects, however, there is a remarkable sameness about most of the major petrochemical complexes. They all date from about 1970, and they are usually associated with a parent crude-oil refinery. They produce a standard slate of products and support one or more training or research institutes. But if China's petrochemical industry originally depended on imported technology and still imports improvements and upgrades, it is also beginning to make significant contributions of its own. One example is the commercialization of deep catalytic cracking (DCC), which maximizes propylene and butylene yields from vacuum gas oil. In developing DCC, the crucial data were obtained from a joint study

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FEBRUARY 24, 1992 C&EN

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SCIENCE/TECHNOLOGY by the Research Institute of Petroleum Processing, the Beijing Engineering Institute, and the Jinan Refinery, all subsidiaries of Sinopec. The first commercial runs were made in a revamped fluid catalytic cracking unit at the Jinan refinery. Total gas yield was about 50% by weight. Propylene constituted about 19% by weight and butylene about 14%. Of considerable interest is the isobutylene content of more than 40% of the total butylene yield. The key to this development was a proprietary catalyst produced in-house. It is claimed that there is no coke formation in the process. Probably of more international interest is development of a catalytic distillation process for production of methyl ferf-butyl ether (MTBE), a gasoline octane improver. The process has been under development at the chemical engineering department of Qinghua University. The basic idea is to feed isobutylene (in a mixed C4 cut) and methanol to a center section of a distillation column. The plates in the reaction zone are equipped with an appropriate catalyst. Following the reaction, unreacted C4s exit from the top of the rectifying section of the column and MTBE exits from the bottom of the stripping section. Qinghua chemical engineers Wang Guang-run and Yuan Nai-ju report that up to 99.8% conversion of the isobutylene to MTBE has been achieved. They have also used the technique in reverse—that is, for the decomposition of ethers to produce highpurity isobutylene or other olefins. Among the possibilities they foresee are alkylation of aromatics and hydrolysis of isobutylene. At Fushun Research Institute of Petroleum & Petrochemicals, a new process for mild hydrocracking of vacuum gas oil is being developed using a locally developed catalyst. At Fushun, the principal hydrocarbon source is domestic crude, of which only about 25% is available for use as an ethylene feedstock. To improve prospects for ethylene generation, the new catalyst has been tailored for this purpose. This involves the inclusion of suitable promoters and added atoms to a basic zeolite. Vacuum gas oil from Shengli crude is the test feedstock. So far the tests have been running about 350 days with good catalyst stability. A major interest in Chinese chemical technology is the utilization of domes20

FEBRUARY 24,1992 C&EN

tic feedstocks to produce surfactants. At Petroleum University in Beijing, a group led by chemical engineer ZhenXiao Wu has developed a new process for the oxidation of liquid n-paraffins to produce secondary alcohols. The work has been in progress since 1964, with pilot studies dating from 1972. By 1988, the group was ready to commercialize. As it has in other countries, the possibility of oxidatively coupling methane to produce olefins has prompted some major catalyst development work in China. What is probably the principal group involved in this effort works at the State Key Laboratory for Catalysis of the Dalian Institute of Chemical Physics. At this institute, one of the efforts aimed at developing suitable catalysts is a project that studies the effects of strontium oxide additives on catalysts containing 20% lanthanum oxide/ calcium oxide. Another group has considered the more general problem of optimizing reaction conditions using several catalysts. These have included magnesium oxide, calcium oxide, strontium carbonate, and barium carbonate. Evaluations of the catalysts were made in a fixed bed at atmospheric pressure. The influences of methane/oxygen concentrations and other operating parameters were investigated. Ethylene production and the aromatization of ethylene on a modified ZSM-5 zeolite were also included in the tests. The further oligomerization of ethylene is a major project at Dalian University of Technology. The idea is to produce linear olefins up to C10 as key intermediates for a variety of processes. There are well-established commercial processes for higher olefins, but at Dalian university the interest is in the lower ones. The principal reaction is direct oligomerization of polymer-grade ethylene using ZrCl 4 / (C2H5)2A1C1 catalysts. These binary catalysts appear to work best when the zirconium-to-aluminum ratio is 50 or higher. The selectivity of the lower olefins also increases as this ratio increases. Another major effort in catalyst development is under way at Tianjin University in connection with rare-earth oxides. At least four distinct applications are being considered in the evaluation program. Interest in the rare-

earth oxides derives from their abundance in China and their corresponding economic value. One application is in improving nickel catalysts for naphtha steam reforming. The Tianjin group has developed a new calcined type of nickel catalyst containing rare-earth oxides incorporated by coprecipitation. The rareearth oxides may be either lanthanum oxide and cerium oxide alone or in combination. All have shown superior performance after a year's operation in a commercial reactor. A second application is rare-earth oxide/copper combinations for the synthesis of lower alcohols. The Tianjin group says that the usual Cu/ZnO/ A1203 catalysts promoted with potassium must be operated at a temperature that somewhat limits the effectiveness of the copper. By incorporating cerium oxide into the catalyst, conversions rise abruptly and stability is maintained at higher temperatures. The third application is rare-earth oxides and perovskite catalysts for the control of air pollution. These types of catalysts have been used for control of auto emissions, but such applications have demanded the presence of precious metals. Researchers hope that the rare-earth oxides can replace the precious metals in this application. The rare-earth oxide of greatest interest is LaNi0 3 , to which copper and cerium ions were introduced. Preliminary testing looks promising. The final application is as a dealkylation catalyst. The dealkylation of toluene to benzene usually employs chromia supported on alumina and is subject to considerable coking and deactivation. Addition of cerium oxide depresses the rate and extent of coking and improves benzene selectivity. It is clear that the expansion of the Chinese petrochemical industry is proceeding both by the import of new technology and, increasingly, by the utilization of home-grown technology. With China's petroleum and petrochemical production now among those of the world leaders in volume, it seems certain that these products will make themselves felt in the international marketplace. For the time being, domestic demands will have to be attended to. However, the necessity of foreign exchange may launch Sinopec and its subsidiaries into the international arena before even the planners in Beijing are

ready.

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