Decomposition of <i>t</i>-Butanethiol into Hydrogen Sulfide without Hydrogen Addition over H-Y and H-beta Zeolites

Abstract

Catalytic direct decomposition of t-butanethiol (TBT) into hydrogen sulfide over zeolites without hydrogen addition was examined as a new desulfurization process for fuel cell systems. TBT is a widely used odorant in pipeline natural gas, and was easily decomposed into hydrogen sulfide and isobutene over H-Y and H-beta at low temperatures of 25-150 . However, catalyst deactivation of H-beta was observed at 60 and oligomerized products of isobutene were observed on the catalyst surface after long reaction times. The deactivation rate of TBT decomposition over H-beta increased with higher acid amounts of H-beta. The amount of oligomerized products deposited on the catalyst increased with lower TBT conversion in the initial stage of reaction. The deposition of oligomerized products and catalyst deactivation decreased after several hours. The amount of the oligomerized products deposited on the catalyst reached approximately 6 wt% after 8 h and remained constant after 125 h over H-beta (Si/Al 92.5) at 150 . The initial TBT conversion was constant during 125 h.

Characteristics of H-beta Zeolite Catalyst for Catalytic Decomposition of <i>t</i>-Butyl Mercaptan

“…Formation of solid hydrocarbon species occurs on the catalyst during the initial reaction stage and the amount of hydrocarbon species decreases gradually in TBM decomposition over H-beta zeolite. The findings of outlet gas analysis also support the results of the previous study 15) .…”

“…TBM is decomposed to hydrogen sulfide and isobutene on acid zeolite catalyst, and produced isobutene is sequentially oligomerized on the catalyst Reaction conditions: TBM concentration 100 ppm balanced by N 2 ; gas flow rate 500 cm 3 min -1 ; catalyst weight 100 mg; reaction time 490 min. and remains as carbon species on the catalyst 15) . We considered that our findings were similar.…”

“…Consequently the gray-colored portion in Fig. 1(b) shows the amount of solid hydrocarbon species formed by sequential oligomerization of isobutene during decomposition of TBM on the catalyst 15) . Trace amounts of hydrocarbon components considered to be lower hydrocarbons rather than isobutene (i.e.…”

“…Our previous study showed that H-Y and H-beta zeolites cause stable decomposition of TBM into hydrogen sulfide at 60 and 150 ; activity is decreased due to carbon species deposition at the beginning of the reaction; and TBM conversion reaches a constant value after a few hours 15) . However, the carbon species formation behavior during the reaction remains unclear.…”

Local Structure Analysis of Active Sites in NiO/γ-Al₂O₃ Catalyst for Dimethyl Sulfide Decomposition: Sulfurization Behavior of Ni Species Using X-ray Absorption Spectroscopy Analysis

“…Recently, we have focused on a new desulfurization process; the catalytic decomposition desulfurization (CDDS) 18) -20) process that decomposes sulfur compounds to hydrogen sulfide over catalyst, and the resul-…”