Paraxylene (PX)

As the growth of the paraxylene (PX) market continues to be driven by increasing global demand, PX prices and margins remain strong and are expected to remain healthy over the next several years. Toluene methylation is an effective and economical solution to maximize PX yields by adding the methyl group from low-cost methanol to the aromatic ring. GTC’s expanding technology portfolio introduces GT-TolAlk, a new way to derive PX while eliminating benzene production.

Process Overview
The feedstock, consisting of methanol and toluene, is processed in the toluene methylation reaction section where the toluene is alkylated into xylenes. The reactor effluent is processed in the fractionation section to produce the mixed xylene product. Unconverted toluene is separated and recycled back to the reaction section. C9+ aromatics fraction is also produced and separated, and is available as feedstock to the transalkylation unit, as the C9+ cut is rich in tri-methyl benzene.

Concept of Toluene Methylation
Traditional toluene-based PX technologies involve
re-arrangement of the alkyl groups though various methods. Benzene is the typical by-product due to insufficient methyl groups compared to phenyl groups. By adding methyl groups to the aromatic ring, GT-TolAlk replenishes the methyl group shortage to yield more xylene over benzene.

 Process Advantages
•    Simple fixed-bed, low-pressure process
•    No hydrogen needed
•    High production capacity
•    Effective addition of methyl group to aromatic ring
•    Very low EB in C8 aromatics; higher PX content compared to reformate xylenes    
•    Potential for zero benzene by-product