Alkylation

GT-TolAlk

As the growth of the paraxylene (pX) market continues to be promising as driven by global demand, pX prices and margins remain strong and expect to stay unchanged over the next few years. Toluene methylation is an effective and economical solution to maximize PX yields by adding 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.The feedstock consists of methanol and toluene which are processed in the toluene methylation reaction section where toluene is selectively methylated to mixed xylene. The reactor effluent is processed in the fractionation section to produce 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.

Process Overview

Current Toluene based PX technologies revolve around re-arrangement of the alkyl groups though various methods. Benzene is the typical by-product due to the imbalance of the methyl group. By adding methyl group to the aromatic ring, toluene methylation process favors xylene production over benzene. The diagram below shows this conversion:

Process Advantages

  • Simple fixed bed, low pressure process
  • No hydrogen is needed
  • High production capacity
  • Effective addition of methyl group to aromatic ring
  • Very low EB
  • No benzene by-product