A process for oligomerizing and oligomerizing olefins to distillate fuels which regenerates a first stage oligomerization catalyst bed and/or a second oligomerization catalyst bed in situ by contact with an oxygen gas at elevated temperature. Purge and pressurization of the oligomerization catalyst bed before regeneration and pressure maintenance after regeneration can be achieved with an inert gas provided by carbon dioxide generated from fermenting starches and sugars from biomass to make alcohol or from carbon burn in the regeneration process. The alcohol can also be dehydrated to olefins to provide the olefin charge stream for oligomerization. The oligomerization catalyst can be restored to full activity. A regeneration process can enable continuous operation.

A feed mixture comprising at least one C.sub.3 olefin and/or at least one C.sub.4 olefin may be contacted with a zeolite catalyst under oligomerization reaction conditions to form a product mixture comprising a plurality of olefin oligomers. The zeolite catalyst, optionally with one or more further modifications, may be selected for operability at high WHSV values that may produce at least C.sub.12 olefins in the product mixture having an average branching index of about 2.2 or less. Under suitable conditions, C.sub.10-C.sub.13 olefins may comprise at least about 25% of the product mixture, M based on total olefin oligomers. Percentage conversion of the at least one C.sub.3 olefin and/or at least one C.sub.4 olefin may impact the average branching index of at least C.sub.12 olefin oligomers and selectivity for C.sub.10-C.sub.13 olefin oligomers. An amount of C.sub.4 olefin in the feed mixture may produce a targeted selectivity for at least C.sub.1 olefins.

Provided is a new crystalline zeolite Fe SSZ-42 prepared by processes for preparing crystalline molecular sieves, particularly large pore zeolites, using an organic templating agent selected from the group consisting of N-benzyl-1,4-diazabicyclo[2.2.2]octane cations and N-benzyl-1-azabicyclo[2.2.2]octane cations.