The invention provides ruthenium-comprising catalysts, and methods of making and using them, for conjugating double bonds in polyunsaturated hydrocarbons, including polyunsaturated fatty acid derivatives, such as natural fats and oils which comprise (contain) more than one carbon to carbon double bond—where the double bonds are separated by, e.g., a methylene, ethylene or propylene or longer group. The invention provides compositions and methods for treating fats and oils comprising “interrupted” (e.g., “methylene-, ethylene- or propylene-interrupted”) double bonds to generate isomers with “conjugated” double bonds. The invention also provides compositions, and methods of making and using them, for making catalysts on a solid support. In one aspect, these catalysts are for alkene isomerization or exchange of alkene hydrogens for other isotopes. The invention provides heterocyclic resin-based compositions, and methods of using them, for making catalysts for alkene isomerization and exchange of hydrogens for deuterium or tritium isotopes.