Process

In a process for carrying out a chemical reaction gaseous reactants are supplied to a first reaction zone including a first catalyst having a first particle equivalent diameter. The first reaction zone is operated such that when the reactants are contacted with the first catalyst a portion of the reactants is converted to the desired product. An intermediate stream of unreacted reactants and the desired product is removed and passed to a second reaction zone including a tubular reactor. Tubes of the reactor are catalyst carriers containing a second catalyst having a second particle equivalent diameter smaller than the first particle equivalent diameter. The second reaction zone is operated such that when the unreacted reactants are contacted with the second catalyst, at least some of the unreacted reactants are converted to the desired product. A product stream is then recovered. Apparatus for carrying out the process is also described.