Abstract: In order to study the silica deposition rule on catalyst bed in coking naphtha hydrogenation unit and verify the protective effect of FHRS-2 silicon trap catalyst, a 2000h simulated operation test was carried out. In addition, the influence of silica deposition on the pore properties of the catalyst was investigated by means of XRF，XRD，XPS，N₂ adsorption-desorption，and the conversion process of silicone-bearing species before and after catalyst regeneration was speculated. The experimental and analytical results showed that the deposition of silicon in the catalyst beds of coking naphtha hydrogenation unit did not decrease uniformly, and in the first and second bed the deposition amount was relatively high. The sensitivity of specific surface area of catalyst to silicon deposition was higher than that of pore volume and pore size. Based on the experimental results, it is speculated that the silicon-containing substance (cyclosiloxane) reacts on the catalyst surface in the high temperature region; and SiO₂ is generated and deposited in the catalyst pore canal during the regeneration process. The activity of main catalyst in downstream can be effectively protected and the operation cycle of coking naphtha hydrogenation unit can be prolonged by loading silicon trap catalyst FHRS-2 in grading mode.

Key words: coking naphtha, hydrogenation, silicon deposition, silicon trap catalyst