Two-Step Conversion of Ethanol to Butadiene

Butadiene is an important chemical commonly used in industry to produce rubber. Butadiene is ordinarily synthesized from a process called "steam cracking" which is a process that takes heavy hydrocarbons and breaks them down into lighter hydrocarbons. Our senior design process aims to present an alternative method for manufacturing butadiene which does not use heavy hydrocarbons as a feedstock. Our objective was to engineer a process which would use only ethanol as feedstock from an existing lignocellulose to bioethanol plant to produce butadiene and determine if it would be economically viable to do so. There are two methods in which to accomplish this design, namely, a one-step method and a two-step method. The one-step method involves the use of a single reactor while the two-step method involves the use of two reactors, but allows for easier operation. Our group decided to engineer a two-step process for the production of butadiene because the two-step process is common practice in the United States when converting ethanol to butadiene. Also, more control of the reactions taking place by selecting two separate catalysts that can be housed in different environments lead us to favor the two-step option. Economics and feasibility of our design were the primary factors used for determining whether this plant design would be favorable. Although the technology for successfully converting ethanol to butadiene has been around since the 1950's, multiple factors must be taken into account before declaring the process favorable.