Synthesis coal-based

Ammonia from coal gasification has been used for fertilizer production at Sasol since the beginning of operations in 1955. In 1964 a dedicated coal-based ammonia synthesis plant was brought on stream. This plant has now been deactivated, and is being replaced with a new faciUty with three times the production capacity. Nitric acid is produced by oxidation and is converted with additional ammonia into ammonium nitrate fertilizers. The products are marketed either as a Hquid or in a soHd form known as Limestone Ammonium Nitrate. Also, two types of explosives are produced from ammonium nitrate. The first is a mixture of fuel oil and porous ammonium nitrate granules. The second type is produced by emulsifying small droplets of ammonium nitrate solution in oil. 

SASOL. SASOL, South Africa, has constmcted a plant to recover 50,000 tons each of 1-pentene and 1-hexene by extractive distillation from Fischer-Tropsch hydrocarbons produced from coal-based synthesis gas. The company is marketing both products primarily as comonomers for LLDPE and HDPE (see Olefin polymers). Although there is still no developed market for 1-pentene in the mid-1990s, the 1-hexene market is well estabhshed. The Fischer-Tropsch technology produces a geometric carbon-number distribution of various odd and even, linear, branched, and alpha and internal olefins however, with additional investment, other odd and even carbon numbers can also be recovered. The Fischer-Tropsch plants were originally constmcted to produce gasoline and other hydrocarbon fuels to fill the lack of petroleum resources in South Africa. 

Feedstocks for the synthesis of monomers of basic polymeric materials must be readily available and inexpensive because they are utilized in polymer synthesis in large quantities, allowing the polymeric materials to be inexpensive. Basic feedstocks are petrochemical and coal-based. 

Methanol is an ideal starting material for the synthesis of many chemicals. It is the most important feedstock for the large-scale commercial production of acetic acid and formaldehyde. Additionally, a variety of other chemicals such as methyl esters, methyl halides and methyl ethers can be produced from it. Tenessee-Eastman s recent pioneering commercialization of a coal-based process for acetic anhydride production illustrates the growing importance of methanol as chemical feedstock. 

In recent years several commercial plants have been constructed for conversion of coal to synthesis gas for chemical manufacturing. These include the Eastman Chemical s acetic anhydride plant, the Ube (Japan) ammonia plant, the SAR (Germany) oxo chemicals plant, and several coal to ammonia plants in China (e.g., Weihe, Huainan, and Lunan). The Ube plant and the SAR plant have since converted to lower-cost opportunity fuels (petroleum coke and residues). The Eastman plant is still operating exclusively on coal. Feedstock changes at the other plants illustrate the vulnerability of coal conversion processes to a changing economic climate. The fact that the Eastman process remains competitive under changing conditions is due to a set of special circumstances that favor a coal-based process. The success of the Eastman chemicals from coal complex demonstrates that synthesis gas from coal is a viable feedstock for some industrial chemicals under certain conditions. 

The intensive investigation of new metal-catalyzed processes for the manufacture of acetic anhydride and acetic acid was driven by the high cost of petroleum and raw materials in the 1970s. As a result, synthesis gas-based technologies were introduced. The major sources of syn gas are coal and heavy petroleum residues. Natural gas or naphtha fractions were also used as feedstocks for synthesis gas. 

The 1973 oil embargo and the ensuing petroleum and natural gas shortages forced the chemical industry to seek new resources for petrochemicals manufacture. About 86% of our domestic carbonaceous fossil fuel resources are coal and only about 2% each are petroleum and natural gas. Thus it is imminent to resort to a coal base for organic chemical products at this time. The manufacture of methanol from natural gas-based synthesis gas is a well-established technology and has been steadily improved over the years. Methanol also can be produced from coal-based synthesis gas in high yield at a... 

Czuppon, T. A. Bui vidas, L J. Which feet nock lor ammonia Hydrocarbon Processing, 58(9) 197-200(1979). Gent, C. W, Ward, S. A, Catalysts in coal-based ammonia plants The Chem. Engineer, 83-87 (Feb. i960). Partridge, L. J. Production of ammonia synthesis gas by purification and shift conversion of gas produced from coal , The Chem. Engineer, 88-90 (Feb. 1980). 

TTistorically, the sources of petrochemical feedstocks have been related directly to the supply of petroleum. Initially, liquified petroleum gases (LPG) supplied this need. Later, as the supply of LPG diminished, naphthas became the primary source (I). The 1973 Arab oil embargo dramatically demonstrated the critical need for alternative sources of fossil carbon. Thus, any development to reduce our dependence on foreign suppliers of petroleum, e.g., an economic coal-based process, should have high priority (2). Hence, there has been a renewal of interest in Fischer-Tropsch processes (3-i4), the catalytic synthesis of primarily C5-C11 hydrocarbons from CO-H2 mixtures. Unfortunately, economic considerations indicate that a synthetic naphtha as cracker feedstock for... 

Sulfur dioxide and dust emissions in the production of acetylene and synthesis gas by the formerly widely used coal-based processes... 

In other cases, the make-up gas contains only H2 and N2 maybe with minor traces of inerts like CH4, Ar, rare gases etc. (Inerts free loop layout). In these cases the synthesis gas is normally generated in front-ends based on coal gasification or with final clean-up of the synthesis gas based on cold box or PSA (Pressure Swing Adsorption) technologies. 

In 1983 Eastman Chemical Company began operating a facility to convert coal to acetic anhydride. This represented the first modem chemicals from coal facility and used coal based synthesis gas to generate acetic anhydride. The lynchpin technologies were a unique, first of its kind, reactive distillation of acetic acid and methanol to generate methyl acetateand the subsequent carbonylation of methyl acetate to generate acetic anhydride. 

The sequence of the remainii steps of synthesis gas preparation is CO shift conversion, removal of H2S and CO2 by Rectisol wash (cold methanol), and liquid nitrogen wash. As in other partial oxidation processes, the H2S is converted to elemental sulfur. Ube Industries, Japan, commissioned a 1,500-tpd ammonia plant in 1984 using the Texaco coal gasification process. An energy consumption of 10.9 Gcal/tonne of ammonia is stated this is lower than the normal quoted f ure of 11.6 Gcal/ tonne of NH3 for coal-based processes 131]. Another 1,000 tpd coal-based ammonia plant is scheduled for startup at Wehei, China, in 1996. 

In a coal-based plant, there are two aqueous streams and one gaseous stream that have to be cleaned up. The raw gas liquor from the coal gasification process contains ammonia and phenols, which are recovered, and the remaining low levels of organics are destroyed in aerobic biodigestors. The FT synthesis of... 

Acetic Anhydride via Methyl Acetate Carbonylation. The second major development, pioneered by Tennessee Eastman (25) is the carbonylation of methyl acetate to acetic anhydride, which also comprises the first example of a totally integrated synthesis gas-based process for such chemistry, dependent entirely on coal as feedstock. 

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