(WO9207921-A1)      Prod. of liq. fuels and starting materials for the chemical industries comprises fractional distn of natural oils; then thermal and/or catalytic cracking and/or reforming of the less volatile components to obtain a mixt. of butane, isobutane and isobutene gases (the 3-5 C fraction) and volatile petroleum (5 + C fraction). The 3-5 fraction is reacted with MeOH or EtOH in the presence of catalysts to form Me or Et tert. Bu ether, but butane is recovered, isomerised to more isobutane, and thermally cracked to isobutene and propene, while unchanged components are recycled.    USE -   The process is applicable to volatile 1-10 C fractions to obtain petroleum fuels, with olefins as a byproduct.    (EP555301-A1)      Prodn. of liq. fuels and starting materials for the chemical industries comprises fractional distn. of natural oils; then thermal and/or catalytic cracking and/or reforming of the less volatile components to obtain a mixt. of butane, isobutane and isobutene gases (the 3-5 C fraction) and volatile petroleum (5+ C fraction). The 3-5 C fraction is reacted with MeOH or EtOH in the presence of catalysts to form Me or Et tert.Bu ether, but butane is recovered, isomerised to more isobutane, and thermally cracked to isobutene and propene, while unchanged components are recycled.    USE -   The process is applicable to volatile 1-10 C fractions to obtain petroleum fuels, with olefins as a byproduct.    (JP6504072-W)      Prodn. of liq. fuels and starting materials for the chemical industries comprises fractional distillation of natural oils; then thermal and/or catalytic cracking and/or reforming of the less volatile components to obtain a mixt. of butane, isobutane and isobutene gases (the 3-5C fraction) and volatile petroleum (5+ C fraction). The 3-5C fraction is reacted with MeOH or EtOH in the presence of catalysts to form Me or Et tert. Bu ether, but butene is recovered, isomerised to more isobutane, and thermally cracked to isobutene and propene, while unchanged components are recycled.    USE -   The process is applicable to volatile 1-10C fractions to obtain petroleum fuels, with olefins as a byproduct.    (EP555301-B1)      Process for producing liquid fuels and chemical raw materials from mineral oil within the framework of a refinery process with process stages for distillation, for thermal and/or catalytic cracking and also where necessary for re-constitution, whereby refinery gas and liquid petroleum gas (LPG) and also benzine (C5+) are distributed into a fractional distillation (VRU) in a gas flow (H2, CO, CO2, C1, C2) and into flows of higher hydrocarbons (C3, C4 and C5+), and a said flow of C4 constituents contains n-butane, isobutane and isobutylene, wherein a refinery process is directly supplemented by the following process stages; - at least a part-current of C4 constituents, together with a flow of methanol or ethanol, is subjected to a catalytic reaction for forming methyl-tertiary-butyl-ether (MTBE) or ethyl-tertiary-butyl-ether (ETBE) - the part of C4 constituents containing n-butane which is not transformed in a catalytic reaction is subjected to isomerisation in which a part of the said n-butane is transformed into isobutane, - at least part of isobutane concerned undergoes a heat-cracking process for forming isobutylene and propylene, - a flow which is the product of said cracking processing for forming isobutylene and propylene, is partly or fully fed back for distribution into a fractional distillation stage.    (US5670703-A)      Refining crude petroleum comprises: (a) generating refinery gas and liquid gas (LPG) and gasolines (C5+) by distilling the crude petroleum; (b) splitting the refinery gas, the liquid gas (LPG) and gasolines by fractionation into a gas flow and flows of higher hydrocarbons (C3, C4, C5+), the higher hydrocarbon flow containing C4 components comprising n-butane, isobutane and isobutylene; (c) subjecting at least a portion of the higher hydrocarbon flow containing C4 components together with a flow of one of methanol and ethanol to a catalytic reaction for producing one of tert-butyl methyl ether (MTBE) and tert-butyl ethyl ether (ETBE); (d) separating an unconverted portion of the n-butane containing C4 components from the catalytic reaction; (e) subjecting the unconverted portion to isomerization for converting a part of the n-butane into isobutane; (f) subjecting at least a part of the isobutane to thermal cracking for forming isobutylene and propylene; and (g) guiding at least a part of a product flow from the thermal cracking back to the splitting step.