UC Santa Barbara

The majority of chemicals the world relies on today are derived from petroleum. Since fossil fuels are non-renewable resources that cannot be sustainably relied upon in the long-term, it is of interest to explore new ways to synthesize commodity chemicals using alternative starting materials. Herein, this work will describe how polymer waste and bio-based precursors can be applied to create chemicals typically derived from virgin petroleum feedstock. In the past century, the world has produced over 7.5 billion metric tonnes of plastics which weigh more than one billion elephants, but 76% of these materials have been discarded into landfills or mismanaged, causing negative externalities such as environmental damage, deleterious health effects, and global economic loss. The research presented demonstrates how multiple types of polyethylene (PE), a frequently used plastic that comprises 36% of all polymers created, can be chemically upgraded using two routes. First, tandem catalytic conversion by platinum supported on gamma-alumina under mild conditions (280 °C without solvent or additives) upcycles PE into high yields (up to 80 wt%) of lubricant grade valuable long-chain alkylaromatics and alkylnaphthenes. Second, a simple, three step sequence of bromination, dehydrobromination, and olefin metathesis reactions, each with respectable yields (86-97%), transforms PE into value-added α,ω-divinyl-functionalized oligomers with shorter, tunable chain lengths that can be used in the synthesis of lubricants and new commodity polymers, with preliminary technoeconomic analyses that demonstrate this three-step process could be economically viable on an industrial scale. Transitioning to renewable bio-based resources to generate energy can be a sustainable method to counter the negative environmental impacts of extracting non-renewable oil from the Earth. Using 1-octen-3-ol, an alcohol that can be derived from nature, high-performance C16H32 diesel was created in three steps with mostly high yields and conversions: (1) dehydration [58% yield], (2) Diels-Alder cyclodimerization [92% conversion], and (3) hydrogenation [95% yield]. With a high gravimetric net heat of combustion of 43.41 MJ/L and a cetane number of 71 which are greater than those for diesel fuel, this high-quality biofuel transcends the performance of diesels used today.