Reactor–Regenerator System for the Dimethyl Ether-to-Olefins Process over HZSM-5 Catalysts: Conceptual Development and Analysis of the Process Variables

Abstract

The dimethyl ether (DME)-to-olefins (DTO) process is an interesting alternative to the methanol-to-olefins process because of the easier production of DME, its higher reactivity, and the moderate deactivation exhibited by HZSM-5 catalysts. A design of the reactor−regenerator system has been developed for the prospective implementation of the DTO process using the kinetic models of two catalysts based on zeolites with different acidities (Si/Al ratios of 15 and 140). These kinetic models have been obtained from DTO experimental runs carried out in a packed bed reactor at 325−400 °C, up to 6.5 g h mol C−1 and 15 h on stream. The reactor−regenerator model considers the activity distribution function of the catalyst in both fluidized bed units by applying the population balance theory. The influence of process variables (space time, temperature, reactant dilution in water or N 2 , catalyst acidity, and mean residence time of the catalyst) on the activity distribution function, conversion, and selectivity to products, mainly olefins, has been studied.

Mechanistic insights into the conversion of dimethyl ether over ZSM-5 catalysts: A combined temperature-programmed surface reaction and microkinetic modelling study

“…14 Considering the activation energies obtained from both vacuum studies and atmospheric studies, it is likely that the atmospheric studies carried out by Perez-Uriarte et al 14 are under mass transfer limitations. Nonetheless, the same group has reported higher activation energies for DME transformation to olefins 82 , which agree with our current work.…”

“…The activation energies also compare favourably with recent studies by Cordero-Lanzac et al over ZSM-5 catalysts. 82 The TPSR studies over ZSM-5 (135) and ( 36) catalysts show that activation energies are generally higher over working catalysts than fresh catalysts. This implies that on DME introduction into the reactor, it is at first relatively easier to carry out AD and ADR reactions.…”

Mechanistic Insights into the Conversion of Dimethyl Ether over ZSM-5 Catalysts: A Combined Temperature Programmed Surface Reaction and Microkinetic Modelling Study

“…10 -6 molDME mcat -3 s -1 (TOF = 3.63 × 10 -6 s -1 ) at pressures of 10 14 Considering the activation energies obtained from both vacuum studies and atmospheric studies, it is likely that the atmospheric studies carried out by Perez-Uriarte et al 14 are under mass transfer limitations. Nonetheless, the same group has reported higher activation energies for DME transformation to olefins 82 , which agree with our current work.…”

“…The activation energies also compare favourably with recent studies by Cordero-Lanzac et al over ZSM-5 catalysts. 82 The TPSR studies over ZSM- 5 (135) and (36) catalysts show that activation energies are generally higher over working catalysts than fresh catalysts. This implies that on DME introduction into the reactor, it is at first relatively easier to carry out AD and ADR reactions.…”

n-Butene Synthesis in the Dimethyl Ether-to-Olefin Reaction over Zeolites

“…Zeolites have been reported as promising catalysts for DTO reactions [7]. Efficient propylene synthesis has been reported using zeolites with topologies such as AEI/CHA [8][9][10], CHA [11][12][13], MFI [14][15][16][17][18], MSE [19][20][21][22], EUO [23], and YFI [24].…”