Lummus/CB&I Hexene-1 from C4 Process (Comonomer Production Technology)

Lummus/CB&I has demonstrated, at the continuous semi-commercial plant scale (2 kty with Tianjin Petrochemical Company of China), an integrated process for producing hexene-1 from refinery and chemical plant by-product mixed C₄ feedstocks. An intermediate product in the process is commercial grade butene-1, which is the predominant comonomer for producing LLDPE. The Lummus technology uses metathesis chemistry to produce a mixture of 1 mol each of ethylene and hexene-3 from 2 mols of butene-1, separates the intermediate products, then isomerizes the hexene-3 to hexene-1 product. Hexene-1 is used primarily as comonomer for producing LLDPE using low temperature, low pressure technology such as the Unipol® process.

Using a combination of Lummus-provided technical information, plus patent literature, SRIC has developed Class-3 process information, and the corresponding capital and manufacturing costs for a fully continuous, grassroots plant to produce 100 kty of hexene-1. We then used this information to prepare factored estimates for a plant with 50 kty hexene-1 capacity and 200 kty hexene-1 capacity. The hexene-1 capital and manufacturing cost estimates are provided below.

Based upon these results, we believe that the Lummus process is commercially viable for a customer that has access to C₄ feedstocks priced at naphtha parity, and wishes to produce a combination of hexene-1 (price = US$1,475/mt) and/or butene-1 as LLDPE comonomer without being burdened by the responsibility for managing a wider business selling the other carbon number linear alpha-olefin (LAO) cuts produced by a conventional wide range LAO process. The one caveat for this conclusion is that the customer has access to a steam cracker for purifying and disposing of the other process by-products at reasonable prices.