Abstract:

The activated carbon (AC) was modified by different acidic reagents (H3PO4，C6H8O7，HNO3). The pore structures and surface chemistry of the samples were characterized by BET，FI-IR，and SEM techniques. The catalytic performance in acetylene hydrochlorination was investigated in a fixed bed reactor. The experimental results show that the pore structures and surface chemistry changes with different acidic reagents though catalytic activities are all increased at various degrees. When nitric acid is used as a modifier, the surface area and pore volume decrease compared to untreated AC, while the average pore diameter increases. The activity of the nitric acid modified catalyst is the best due to greatly improve the content of oxygen-containing acidic groups. The conversion of acetylene is up to 71.8％; When phosphoric acid is used as a modifier, the reduction of specific surface area is the largest, whoever, its activity increases because of the introduction of phosphate. The activity of the catalyst treated with citric acid does not increase. In addition, it is found that high concentration of nitric acid or too long time treating does not help to improve the activity of the catalyst due to a strong corrosion of nitric acid. The catalytic activity is the best at nitric acid concentration of 5 mol/L and 6h.

Key words: activated carbon, acid modification, acetylene hydrochlorination, catalyst