Oils from plants and animal fats are hydrolyzed to fatty acids for a Kolbe reaction. The invention relates to a high productivity Kolbe reaction process for electrochemically decarboxylating C4-C28 fatty acids derived from sources selected based on their saturated and unsaturated fatty acid content in order to lower anodic passivation voltage during synthesis of C6-C54 hydrocarbons. The C6-C54 hydrocarbons may undergo olefin metathesis and/or hydroisomerization reaction processes to synthesize heavy fuel oil, diesel fuel, kerosene fuel, lubricant base oil, and linear alpha olefin products useful as precursors for polymers, detergents, and other fine chemicals.

In a process for producing para-xylene, a feed comprising a mixture of xylene isomers, olefinic unsaturated contaminants and oxygenate contaminants is supplied to a para-xylene recovery unit to recover para-xylene and produce a para-xylene depleted residual stream. The para-xylene depleted residual stream is then contacted with a xylene isomerization catalyst in a xylene isomerization zone under liquid phase conditions effective to isomerize xylenes and produce an isomerized product having a higher para-xylene content than the para-xylene depleted residual stream. The isomerized product is then recycled to the para-xylene recovery unit. At least one of the feed, the para-xylene depleted residual stream and the isomerized product is contacted with a solid acid catalyst in a treatment zone under conditions effective to reduce the level of olefinic unsaturated contaminants and oxygenate contaminants therein and produce a treated stream.