Plastics - the second generation - from petrochemicals

The dramatic growth of the chemical industry was fuelled in the main by petroleum and the new technologies of the petrochemical industry. The industry had its origins in the US, where cheap natural gas, the thermal cracking of natural gas liquids and catalytic cracking in refineries contributed abundant raw material supplies, particularly olefins. By the early 1950s the industry was taking root in Europe, with the emphasis there on naphtha cracking, as Europe lacked the natural gas liquids. It did, however, have adequate naphtha from the new refineries constructed principally to satisfy the growing demand for fuel oil.

Australia at that time had neither petroleum resources nor a significant crude oil refining industry, although limited processing of oil fractions was carried out in small units such as that operated by Bitumen Oil Refineries (Australia) Ltd. ('Boral', now Boral Ltd) at Matraville, NSW. Expansion-minded Australian manufacturers of chemicals looked enviously at the raw materials available on the other side of the globe, meanwhile exploring the limited alternative possibilities for manufacturing them here. The key intermediate was ethylene which, being a gas, could not be transported economically to Australia. As early as 1948, Timbrol Ltd. had constructed a pilot plant for the manufacture of ethylene glycol by the chlorhydrin route. Ethylene was obtained by the catalytic dehydration of alcohol (ethanol), a fermentation product in abundant supply from the Queensland sugar industry. The Timbrol plant operated successfully but was never scaled up as under most circumstances the cost of ethanol makes it uneconomic. Indeed the reverse, the synthesis of ethanol by the hydration of ethylene is the industrial norm. Australia's problem was to find a cheaper route to ethylene in the face of limited outlets. Petrochemical ethylene plants are complicated and expensive, particularly the low temperature distillation step necessary to separate the compounds with one and two carbon atoms in the cracked gas stream. Consequently product cost is extremely scale-sensitive. Three different approaches to this problem were tried.

1. As mentioned earlier ICI Australia established polyethylene production using ethanol dehydration meanwhile developing additional ethylene demand at the site for the manufacture of vinyl chloride/PVC and ethylene oxide. When total ethylene demand justified it, a conventional petrochemical ethylene plant was constructed at Shell's Clyde refinery, the ethylene being transported by pipeline to Botany. Subsequently ICI Australia erected a naphtha cracker and thereby established a petrochemical and plastics complex under a single management.
2. Several companies pooled their ethylene demand (see 'The Altona Petrochemicals Complex' (pp 709-714) to justify the construction of an ethylene cracker and purification plant near Melbourne.
3. The earliest entry in the petrochemical stakes in Australia was a new company, Petroleum and Chemical Corporation (Australia) Ltd. (PACCAL). The company was formed in 1953 to manufacture gas to supplement the coal gas then used for Sydney's gas supply. The process to be used was the thermal cracking of heavy residual oil in regenerative furnaces. The oil was supplied by Boral, which had a substantial minority interest in the new venture.

Australian Academy of Technological Sciences and Engineering