Petrochemically Generated Acetylene

Acetylene which is won petrochemically is usually offered in very large quantities at the respective plant as acetylene is no longer of prime importance in the chemical industry as a raw material for chemical products. One advantage over carbide acetylene is that there are no by-products and therefore no facilities required for their disposal. 

The petrochemical manufacture of acetylene is based on reprocessing cracked gases with the ensuing extraction of C2 hydrocarbons [8.4]. 

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The feedstock can be olefin-rich light hydrocarbons in the carbon range C4 to Cg, and the ideal feedstocks are C4 and C5 streams generated in the steam cracker. Diolefins and acetylenes in the feedstock can be partially hydrogenated to olefins, or the diolefins extracted for other petrochemical applications. Other possible feedstocks are MTBE Rafifinate-2, aromatics plant raffinate and refinery streams that are rich in olefins, such as light naphthas from an FCCU, coker or visbreaker. Refinery streams do not require pretreatment or hydrogenation of dienes - there is no limit on feed aromatic or diene content. 

One of the oldest processes for generating small-molecule organics—predating the modern petrochemical industry—is the process of making acetylene. Acetylene results when calcium carbide, synthesized from limestone and coke at a temperature exceeding 2000°C, is reacted with water. Direct addition of HCl to acetylene over a mercury chlo-ride/activated carbon catalyst yields VCM. VCM is washed with water and base, and then distilled. Wash water and spent catalyst must be treated to remove and recycle mercury. 

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