Published November 2014
This report presents a technical and economic evaluation of three technologies used in the production of benzene, toluene, and xylenes (BTX). The feedstocks for the BTX processes are C3-C4 range aliphatic/olefinic hydrocarbons. PEP Reports 129A, 129B, and 182B (published in 1996, 2006, and 2008, respectively), covered BTX technologies based on the catalytic reforming of light naphtha or pyrolysis gasoline.
The current report, however, focuses on BTX produced from liquefied petroleum gas (LPG) as individual, refined products that serve as feedstocks for several other commercially important derivative chemicals. Hence, the starting materials covered in this report differ from those in previous reports covering aromatics.
From the perspective of feedstocks, LPG has a cost advantage over light naphtha-range hydrocarbons. However, many LPG production regions are remote, resulting in high transportation costs, leading LPG producers to look for ways to convert LPG (or C3-C4-rich streams) into more valuable products that are in higher demand, such as BTX. The three technologies analyzed in this report are UOP-BP Cyclar technology, SINOPEC Luoyang GTA technology, and Mitsubishi-Chiyoda Z-Forming technology.
UOP-BP's Cyclar technology is based on a bifunctional catalyst consisting of a metal (gallium) modified zeolite (ZSM-5) base material. The highlight of this process is the proprietary continuous catalyst regeneration system (CCR system), a feature used by UOP for the last 40 years. Another important feature of the process is the type of reforming system, which consists of a series of vertically stacked reactors in which catalyst flows down under gravity in the form of a dense medium and reactants flow through the catalyst bed in a radial direction. Operating conditions are 896-1,022°F (480-550°C) at <100 psia. BTX yield can be up to 60-65 wt%. Feed to process is LPG or light naphtha. For BTX separation, only simple distillation (SD) is used.
SINOPEC Luoyang's GTA technology is also based on a bifunctional catalyst consisting of a metal (undisclosed, but likely zinc or gallium) modified zeolite (ZSM-5) base material. The reforming reactors are of an adiabatic, fixed-bed type. Operating conditions are 860-986°F (460-530°C) at <70 psia. BTX yield can be up to 55-60 wt%. Feed to process is C4-rich olefinic streams. For BTX separation, only SD is used.
Mitsubishi-Chiyoda's Z-Forming technology is also based on a bifunctional catalyst consisting of a metal (undisclosed, but likely zinc) modified zeolite (ZSM-5) base material. The reforming reactors are of an adiabatic, fixed-bed type. Operating conditions are 932-1,112°F (500-600°C) at <100 psia. BTX yield can be up to 55-58 wt%. Feed to process is LPG or light naphtha. For BTX separation, only SD is used.
