Water inhibits the conversion and coking of olefins on SAPO-34

Luo, Mingjian; Fu, Yadong; Hu, Bao Qing; Wang, Dakang; Wang, Baohui; Mao, Guoliang

doi:10.1016/j.apcata.2018.11.017

Cited by 17 publications

(31 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…According to the density functional theory (DFT) 43 , 44 and experimental results 41 , 45 , 46 , the methylbenzenes and methylnaphthalene retained in SAPO-34 zeolites can serve as activated carbonaceous species 46 , 47 . In contrast, the phenanthrene, pyrene or carbonaceous species with higher molecular weight (MW) 48 exhibit very low reactivity 44 , 46 . Our MD simulations show that the loading of methylbenzenes and methylnaphthalene in CHA cage has only slightly affected the molecular diffusion, i.e., the ratio of diffusivity in cage loading with carbonaceous species D load to that of empty cage D empty is 0.3~1.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Imaging spatiotemporal evolution of molecules and active sites in zeolite catalyst during methanol-to-olefins reaction

Gao

Liu

et al. 2020

Nat Commun

View full text Add to dashboard Cite

Direct visualization of spatiotemporal evolution of molecules and active sites during chemical transformation in individual catalyst crystal will accelerate the intuitive understanding of heterogeneous catalysis. So far, widespread imaging techniques can only provide limited information either with large probe molecules or in model catalyst of large size, which are beyond the interests of industrial catalysis. Herein, we demonstrate a feasible deep data approach via synergy of multiscale reaction-diffusion simulation and super-resolution structured illumination microscopy to illustrate the dynamical evolution of spatiotemporal distributions of gas molecules, carbonaceous species and acid sites in SAPO-34 zeolite crystals of several micrometers that are typically used in industrial methanol-to-olefins process. The profound insights into the inadequate utilization of activated acid sites and rapid deactivation are unveiled. The notable elucidation of molecular reaction-diffusion process at the scale of single catalyst crystal via this approach opens an interesting method for mechanism study in materials synthesis and catalysis.

show abstract

Section: Resultsmentioning

confidence: 99%

“…In addition, the adsorption bands at ~561 nm (PH n + ) and ~640 nm (PYR n + ) are relatively unconspicuous in the small crystal. It has been recently shown that carbonaceous species located in adjacent cavities can be further connected through windows during reaction to form heavier carbonaceous species 48 , 55 . As can be seen from Fig.…”

Section: Resultsmentioning

confidence: 99%

Imaging spatiotemporal evolution of molecules and active sites in zeolite catalyst during methanol-to-olefins reaction

Gao

Liu

et al. 2020

Nat Commun

View full text Add to dashboard Cite

show abstract

“…These hydrocarbon pool species (HCPs), typically including the methyled-benzene carbocations 10 , 11 and cyclopentadienyl species 12 , 13 , are decisive for light olefins selectivity, owning to the altering of acidity 14 , reaction paths 15 , kinetics 8 , 9 , molecular transport 16 , and among others. However, the HCPs are also coke precursors that can readily evolve to polycyclic aromatic hydrocarbons (PAHs), the typical coke species, through cyclization 17 and cross-linked mechanism 18 , 19 , accelerating catalyst deactivation 20 . Therefore, such dual-role of HCPs impedes achieving superior light olefins selectivity while maintaining long catalyst lifetime in MTO over zeolitic catalyst.…”

Section: Introductionmentioning

confidence: 99%

Directed transforming of coke to active intermediates in methanol-to-olefins catalyst to boost light olefins selectivity

et al. 2021

View full text Add to dashboard Cite

Methanol-to-olefins (MTO), the most important catalytic process producing ethylene and propylene from non-oil feedstocks (coal, natural gas, biomass, CO2, etc.), is hindered by rapid catalyst deactivation due to coke deposition. Common practice to recover catalyst activity, i.e. removing coke via air combustion or steam gasification, unavoidably eliminates the active hydrocarbon pool species (HCPs) favoring light olefins formation. Density functional theory calculations and structured illumination microscopy reveal that naphthalenic cations, active HCPs enhancing ethylene production, are highly stable within SAPO-34 zeolites at high temperature. Here, we demonstrate a strategy of directly transforming coke to naphthalenic species in SAPO-34 zeolites via steam cracking. Fluidized bed reactor-regenerator pilot experiments show that an unexpectedly high light olefins selectivity of 85% is achieved in MTO reaction with 88% valuable CO and H2 and negligible CO2 as byproducts from regeneration under industrial-alike continuous operations. This strategy significantly boosts the economics and sustainability of MTO process.

show abstract

“…From these results, it can be stated that high temperatures and low water content lead to high conversions at low time on stream values but faster catalyst deactivation. On the other hand, a decrease in the temperature or an increase in the amount of co-fed water makes the initial conversion drop but softens the deactivation rate, which could enlarge the catalyst lifetime [39]. A similar trend is followed by the olefin yields (Fig.…”

Section: Packed Bed Reactormentioning

confidence: 65%

“…) or co-fed) in the formation of coke and catalyst deactivation [37][38][39]. This is a nonselective deactivation model, which considers the same activity in all the steps of the reaction network.…”

Section: Reaction Networkmentioning

confidence: 99%

A comprehensive approach for designing different configurations of isothermal reactors with fast catalyst deactivation

Cordero-Lanzac

Aguayo

Gayubo

et al. 2020

Chemical Engineering Journal

View full text Add to dashboard Cite

A methodology for simulating the performance of different reactor configurations for processes with complex reaction networks and fast catalyst deactivation has been proposed. These reaction configurations are: packed bed, moving bed and fluidized bed reactors with and without catalyst circulation. From kinetic parameters collected in a packed bed reactor and a rigorous consideration of the activity, modifications in the convection-dispersion-reaction equation have led to the prediction of the catalyst performance in each reactor configuration. Circulating fluidized bed reactor has been simulated with an original model of parallel compartments, which allows for determining its performance in the steady state from the evolution of the transitory period. The methodology has been used for simulating the dynamics of SAPO-34 fast deactivation during the methanol-to-olefins (MTO) process. For each reactor configuration, concentration profiles and their evolution with time have been simulated, thus predicting the effect of reaction conditions and water content (formed and/or cofed) on the activity profile or the activity distribution function (in the case of circulating fluidized bed reactor). The olefin yield and distribution have also been compared for each reactor configuration.

show abstract

Water inhibits the conversion and coking of olefins on SAPO-34

Cited by 17 publications

References 59 publications

Imaging spatiotemporal evolution of molecules and active sites in zeolite catalyst during methanol-to-olefins reaction

Imaging spatiotemporal evolution of molecules and active sites in zeolite catalyst during methanol-to-olefins reaction

Directed transforming of coke to active intermediates in methanol-to-olefins catalyst to boost light olefins selectivity

A comprehensive approach for designing different configurations of isothermal reactors with fast catalyst deactivation

Contact Info

Product

Resources

About