Abstract: Pyridine bases are produced in higher yield from at least one of aliphatic carbonyl compounds and ammonia by reaction at 350.degree. to 550.degree.C under the atmospheric pressure at a space velocity of 100 to 10,000 hr.sup.-.sup.1 in the presence of a catalyst prepared by immersing silica-alumina or a silica-alumina mixture containing a promoter in an aqueous solution of ammonium halide such as ammonium chloride, ammonium iodide or ammonium bromide at a concentration of not more than 20% by weight at room temperature to 80.degree.C, washing the immersed silica-alumina or the mixture with water, and drying and calcining the same at 300.degree.C or higher. Regeneration of the catalyst after the reaction can be carried out for a much shortened time.

Abstract: Alkylpyridines such as 2-picoline and 4-picoline are prepared by contacting acetaldehyde and ammonia in a gaseous phase with a phosphate of two metals such as cobalt magnesium phosphate, cobalt aluminum phosphate or lead aluminum phosphate, impregnated with an aqueous solution of phosphoric acid or ammonium phosphate, as a catalyst, at a temperature of 350.degree. to 500.degree.C and a space velocity of 200 to 2,000 Hr.sup.-.sup.1. Silica-alumina and a promoter can be added to the catalyst. The impregnated catalyst has a higher catalytic activity and holds the initial high activity even after a considerable number of regeneration.