(652d) An Experimental Study of High-Pressure, Multi-Phase Reactions between Sulfur and Hydrocarbons; Strategies to Enhance Reaction Rate for Process Intensification

Sulfurized hydrocarbon materials play a wide role in the chemical process industry. Due to the thermodynamic and kinetic limitations of sulfur in reacting with most hydrocarbon systems, most industrial processes are operated in batch reactors. In order to gain the benefits of continuous operation and production, the reaction rate must be significantly increased through changes in the operating conditions and/or the use of catalysts.

In the current work, the control processes were conducted under the same conditions as in industry, and compared to reactions in ‘intensified’ process conditions. The control reactions were carried out at 160-190^oC at low pressure, controlled by the vapor pressure of the hydrocarbons, with a vapor space comprising approximately 20% of the vessel. Initially, the system shows a liquid sulfur-rich phase and a hydrocarbon-rich phase is formed, with a vapor space rich in hydrocarbon and intermediates such as H₂S above it. Within an hour, the liquid sulfur phase is consumed, leaving a single liquid phase containing sulfur, unreacted hydrocarbons and sulfurized products. High conversion requires a hold time of approximately 5-10 hours.

In order to significantly increase the reaction rate such that a batch-to-continuous transition in manufacturing can occur, three methods were studied using a windowed, variable-volume, Inconel vessel rated to 300^oC and 40000psi. First, at 160-190^oC, the pressure was increased to prevent the formation of a vapor phase, forcing all the volatile by-products and intermediates to remain dissolved in the liquid phase(s). Second, the temperature was increased up to 250^oC to enhance reaction rate at a sufficient pressure to suppress the formation of a vapor phase. Third, attempts were made to identify effective homogenous or heterogeneous catalysts. The reaction results will be discussed in detail in the presentation.