Method for conducting exothermic reactions

A method for conducting exothermic reactions in a fixed catalyst bed, comprising:

• (a) preheating the reactants in a liquid feed stream to a temperature sufficient to initiate the exothermic reaction in the catalyst bed;
• (b) feeding the preheated reactants to the top of a fixed catalyst bed wherein the exothermic reaction is initiated to form a reaction mixture containing reactants and reaction products while releasing a positive heat of reaction;
• (c) allowing said reaction mixture to pass downwardly through the fixed catalyst bed wherein the exothermic reaction continues so as to increase the concentration of the reaction products in the reaction mixture to the desired level;
• (d) controlling the pressure on the fixed catalyst bed such that a portion of the reaction mixture is vaporized by the positive heat of reaction;
• (e) withdrawing the partially vaporized reaction mixture containing reaction products from the bottom of the catalyst bed at a temperature higher than the temperature of the preheated feed stream;
• and
• (f) indirectly exchanging heat between the withdrawn reaction mixture and the feed stream to provide the heat for step (a) after the reaction has been initiated, the transferred heat being substantially equal to that required to heat the feed stream to the temperature necessary to initiate the exothermic reaction in the catalyst bed, and the net heat gain between the unheated feed stream and the withdrawn reaction mixture after indirect exchange with the feed stream being equal to the exothermic heat of reaction in the catalyst bed.