6.2.2. Effect of Pressure

Typically, pressure is one of the most effective parameters influencing acetylene conversion and ethylene selectivity. In detail, the pressure could change, both the adsorption coefficients of catalysts and the partial pressure of the participated components on the catalyst. Figure 8a,b shows the effect of operating pressure on acetylene conversion, ethylene selectivity, and product distribution. Based on the experiments, although increasing pressure improves acetylene conversion, selectivity decreases sharply in pressure range 15–18 bar and after that decreases gradually. Typically, pressure increases the diffusivity and adsorption of components in the surface of the catalyst and results in a higher conversion factor. It appears that the main side product is 1-butane and increasing operating pressure increases the rate of side products in the system. *Processes* **2019**, *7*, x FOR PEER REVIEW 14 of 22 of operating pressure on acetylene conversion, ethylene selectivity, and product distribution. Based on the experiments, although increasing pressure improves acetylene conversion, selectivity decreases sharply in pressure range 15‒18 bar and after that decreases gradually. Typically, pressure increases the diffusivity and adsorption of components in the surface of the catalyst and results in a

**Figure 8.** Effect of pressure on (a) acetylene conversion, ethylene selectivity, and (b) product distribution at 35 °C and hydrogen to acetylene ratio 0.9 and GHSV 3500 1/h. **Figure 8.** Effect of pressure on (**a**) acetylene conversion, ethylene selectivity, and (**b**) product distribution at 35 ◦C and hydrogen to acetylene ratio 0.9 and GHSV 3500 1/h.

6.2.3. Effect of Temperature
