(521ce) Mercaptan Removal from Natural Gas: An Evaluation of Metal Oxides and Aluminum Silicates As Catalysts

Methanethiol, commonly referred to as methyl mercaptan, is a type of sulfur-based compound often found in natural gas streams. This compound is responsible for unpleasant odors and can lead to pipeline corrosion. To improve natural gas quality, metal oxides and aluminum silicates have been examined as potential catalysts for removing mercaptan. This study explored the effectiveness of these materials in a fixed-bed reactor with simulated natural gas streams. Catalyst performance in methyl mercaptan removal depends on temperature, pressure, and gas flow rate. The adsorbent/catalysts were thoroughly characterized using Brunauer-Emmett-Teller (BET), Scanning Electron Microscope (SEM), Energy-Dispersive X-ray Spectrometry (EDS), and X-ray Photoelectron Spectroscopy (XPS).

The results showed that metal oxides, particularly a commercial catalyst called Select HP, composed mainly of copper, manganese, and zinc oxides, exhibited promising methyl mercaptan removal capabilities. Select HP achieved a breakthrough time of 361 minutes at 75°C, 200 psi, 36 ml/min, and 100 ppm CH₃SH. These findings offer valuable insights for developing new catalysts that combine metal oxides to enhance adsorption while minimizing the formation of reaction by-products such as dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) during methyl mercaptan removal.

An alumino-silicate (Halloysite Pure) was impregnated with copper, zinc, nickel, magnesium, and manganese oxides to evaluate their impact on removing methyl mercaptan from natural gas. The addition of metal oxides to the alumino-silicate surface resulted in a sulfur capacity of 1.29 gS/gcatalyst at 25°C, 200 psi, 36 ml/min, and 200 ppm methyl mercaptan, while Select HP's sulfur capacity under the same conditions was 0.38 gS/gcatalyst. Future experiments will be conducted at higher temperatures to determine whether the performance of the new UL catalyst improves methyl mercaptan removal at industrial operating temperature ranges.