Spiral-wound organic solvent membrane modules for dewaxing solvent recovery

The petrochemical industry is typically energy-intensive, involving frequent and intricate separation processes. SINOPEC is a globally recognized lubricant manufacturer and distributor, with a substantial production capacity exceeding 1.7 million tonnes in 2022. The dewaxing solvent recovery process in lubricant production necessitates a multi-stage flash and distillation treatment, resulting in substantial energy consumption and high costs. Utilizing organic solvent nanofiltration (OSN) membranes offers a feasible alternative approach to address this issue. A series of thin film composite OSN membranes with varying molecule weight cut-offs were prepared through precise adjustment of the chemical composition and proportion of the organic co-monomers. The application potential of the optimized membranes in the lubricant dewaxing solvent recovery was evaluated using lubricant base oil derived from the actual production line, specifically light deasphalted oil and vacuum cut2. The membrane exhibited a rejection of 99.3 % for light deasphalted oil and 95.6 % for vacuum cut2, with corresponding fluxes of 16.8 and 13.4 LMH under 2 MPa, respectively. Based on this, spiral-wound membrane modules (1.8″ × 12″) were fabricated and their suitability for dewaxing solvent recovery was further validated. The fabrication of spiral-wound membrane modules (8″ × 40″) is in progress, with intentions to conduct a pilot plant trial on the lubricant oil manufacturing line.