The present disclosure provides methods to produce para-xylene, toluene, and other compounds from renewable sources (e.g., cellulose, hemicellulose) and ethylene in the presence of an acid, such as a Lewis acid. For example, cellulose and/or hemicellulose may be converted into 2,5-dimethylfuran (DMF) and 2-methylfuran, which may be converted into para-xylene and toluene, respectively. In particular, para-xylene can then be oxidized to form terephthalic acid.

Oligomerization processes include the steps of introducing a monomer containing a C.sub.3 to C.sub.30 olefin and a chemically-treated solid oxide into a reaction zone, and oligomerizing the monomer to form an oligomer product in the reaction zone. Fluorided silica-coated alumina and fluorided-chlorided silica-coated alumina are illustrative chemically-treated solid oxides that can be used in the oligomerization processes.

Oligomerization processes include the steps of introducing a monomer containing a C.sub.3 to C.sub.30 olefin and a chemically-treated solid oxide into a reaction zone, and oligomerizing the monomer to form an oligomer product in the reaction zone. Fluorided silica-coated alumina and fluorided-chlorided silica-coated alumina are illustrative chemically-treated solid oxides that can be used in the oligomerization processes.

Systems and methods for processing a C.sub.3 and C.sub.4 hydrocarbon mixture have been disclosed. The C.sub.3 and C.sub.4 hydrocarbon mixture is separated to remove propane from C.sub.4 hydrocarbons. The resulting C.sub.4 hydrocarbons are then processed in an isomerization unit to produce additional isobutane. The isobutane of the isomerization unit effluent is dehydrogenated in a dehydrogenation unit to produce isobutene. The resulting isobutene is reacted with an alkanol to produce an alkyl tert-butyl ether.