*1.2. Hydrogenation Method*

The Front-End and Tailed-End are two common methods in acetylene hydrogenation, which differ in the reactor structure and process arrangements. In the Front-End method, the feed stream, which may contain up to 40% hydrogen, directly enters into the hydrogenation reactor and feeds temperature, is the only manipulated variable. Gobbo et al. modeled and optimized the Front-End acetylene hydrogenation process considering catalyst deactivation [19]. They calculated the dynamic optimal trajectory of feed temperature to control acetylene concentration at desired level. In the Tail-End method, hydrogen is separated from the effluent stream from steam cracker. In this method, the feed temperature and hydrogen concentration in the feed stream are manipulated variables. Aeowjaroenlap et al. modeled the Tailed-End hydrogenation reactors, based on the mass and energy balance equations at dynamic condition [20]. To obtain the optimum operating condition, a single objective dynamic optimization problem was formulated to maximize process economics. The inlet temperature and hydrogen concentration were selected as the decision variables. The results showed that applying optimal operation condition on the system increases process economics about 10%.
