Ferrierite Catalyst Research Articles

Associative-Distal Mechanism of the Haber–Bosch Process on a Ferrierite Catalyst with Spatially Isolated Dual Molybdenum Sites

Associative-Distal Mechanism of the Haber–Bosch Process on a Ferrierite Catalyst with Spatially Isolated Dual Molybdenum Sites

Enhanced Selectivity and Stability of Finned Ferrierite Catalysts in Butene Isomerization.

Designing zeolite catalysts with improved mass transport properties is crucial for restrictive networks of either one- or two-dimensional pore topologies. Here, we demonstrate the synthesis of finned ferrierite (FER), a commercial zeolite with two-dimensional pores, where protrusions on crystal surfaces behave as pseudo nanoparticles. Catalytic tests of 1-butene isomerization reveal a 3-fold enhancement of catalyst lifetime and an increase of 12 % selectivity to isobutene for finned samples compared to corresponding seeds. Electron tomography was used to confirm the identical crystallographic registry of fins and seeds. Time-resolved titration of Brønsted acid sites confirmed the improved mass transport properties of finned ferrierite compared to conventional analogues. These findings highlight the advantages of introducing fins through facile and tunable post-synthesis modification to impart material properties that are otherwise unattainable by conventional synthesis methods.

Enhanced Selectivity and Stability of Finned Ferrierite Catalysts in Butene Isomerization

AbstractDesigning zeolite catalysts with improved mass transport properties is crucial for restrictive networks of either one‐ or two‐dimensional pore topologies. Here, we demonstrate the synthesis of finned ferrierite (FER), a commercial zeolite with two‐dimensional pores, where protrusions on crystal surfaces behave as pseudo nanoparticles. Catalytic tests of 1‐butene isomerization reveal a 3‐fold enhancement of catalyst lifetime and an increase of 12 % selectivity to isobutene for finned samples compared to corresponding seeds. Electron tomography was used to confirm the identical crystallographic registry of fins and seeds. Time‐resolved titration of Brønsted acid sites confirmed the improved mass transport properties of finned ferrierite compared to conventional analogues. These findings highlight the advantages of introducing fins through facile and tunable post‐synthesis modification to impart material properties that are otherwise unattainable by conventional synthesis methods.

Comparison of doped ZSM-5 and ferrierite catalysts in the dehydration of bioethanol to ethylene in a flow reactor

This study describes the performance of ten zeolite catalysts, doped with various elements, in the dehydration of bioethanol. As acidic catalysts are known as profitable for this reaction, ZSM-5 and ferrierite (FER) based catalysts were selected to use. The synthesized catalysts were characterized by different analytical methods (XRF, XRD, DRIFT, N2-physisorption and TPD-NH3). A high space velocity (15 h−1) and low temperature (220 °C) were used to study the differences on catalyst activity. The Ti-deZSM-5 was the most active catalyst with 48% conversion. Subsequent the screening tests were carried out in a flow micro-reactor at different operating conditions (220–250–280 °C and WHSV 7–11–15 h−1). Ti-deZSM-5 showed the highest bioethanol conversion (96%) and selectivity to ethylene (88%) at 280 °C and WHSV of 7 h−1 while in the case of FER it resulted in very small or no selectivity to ethylene. The results show that catalysts from the ZSM-5 group are more suitable for the dehydration of bioethanol to ethylene than FER catalysts.

Kinetic modeling for direct synthesis of dimethyl ether from syngas over a hybrid Cu/ZnO/Al2O3/ferrierite catalyst

A kinetic model for the direct synthesis of dimethyl ether (DME) from syngas over a hybridized Cu/ZnO/Al2O3/ferrierite (CZA/FER) catalyst was developed. Kinetic parameters including reaction rate and equilibrium constants were estimated by fitting experimental data for the hybrid catalyst, and these were compared with the reported values for conventional catalysts. High activation energies for the hybrid CZA/FER catalyst showed that the methanol synthesis step may have more control over the rate than the methanol dehydration step. This may be attributed to the core-shell structure of the hybrid catalyst in such a way that the diffusion resistance plausibly plays an important role in the kinetics; this feature was reflected in our estimated kinetic parameters. Using the developed kinetic model, a temperature between 200 and 220 °C was determined for thermal energy efficiency, and a further analysis provided the optimal range of the total pressure and space velocity.

Vegetable Oil to Biolubricants: Review on Advanced Porous Catalysts

Vegetable oil is one of the most potential sustainable feedstocks to produce fuels and chemicals. The review emphasizes isomerization of fatty acid as an important path for biolubricant production. The role of solid acid catalysts, including zeolites, was highlighted to design better isomerization catalysts. The isomerization is a favored mesoporous site with intermediate Bronsted acid strength, which is also enhanced after metal doping on a porous surface. The hierarchical ferrierite (FER) catalyst showed the best selective isomerization with the 10-membered ring cavities, which can be regenerated easily. FER can be produced using a low-cost organic structure-directing agent. The possibility to design two-dimensional pore zeolites with pore mouth selectivity was also discussed. Moreover, the challenges for biolubricant formulation, with focus on palm oil, were also discussed with a detailed comparison to other vegetable oils. The highest palm oil conversion was achieved over the base catalyst, namely, Sr...

On the mechanism of high-temperature N2O decomposition over Fe-FER in the presence of NO

The role of NO in the N2O decomposition under conditions relevant to its formation by NH3 oxidation during nitric acid production over iron-containing ferrierite (Fe-FER) catalyst was investigated. In particular, the relative productions of O2 and NO2 during the high-temperature decomposition of N2O over Fe-FER as the result of the direct recombination of adsorbed atomic oxygen (Oat) and of NO oxidation steps, respectively, were evaluated. These results proved the enhanced role of the direct Oat recombination step at higher temperatures but surprisingly also indicated persistent and substantial elimination of N2O due to NO oxidation during the formation of NO2 at T ≥ 800 °C.

Designing ferrierite-based catalysts with improved properties for skeletal isomerization of n-butene to isobutene

The crystal morphology and size of ferrierite catalysts were controlled by a suite of crystallization methods and structure-directing agents.

Effect of copper surface area and acidic sites to intrinsic catalytic activity for dimethyl ether synthesis from biomass-derived syngas

The crucial effects of copper surface area and acidic sites to intrinsic catalytic activity on the bifunctional catalysts such as Cu-ZnO/Al2O3 and Cu-ZnO-Al2O3/Zr-modified ferrierite catalysts have been investigated to find out the correlation between these two characteristics for the direct synthesis of dimethyl ether (DME) from biomass-derived syngas. The well-dispersed copper particles with a high reducibility as well as a large amount of weak acidic sites on bifunctional catalysts are responsible for their high catalytic performance. The high activity for methanol synthesis could be obtained by designing a high surface area of metallic copper with a low aggregation character, however, the quantity of the acidic sites on solid-acid components is also crucial factor for a high DME yield than the surface area of copper, which could be obtained by preparing proper bifunctional catalysts. It is mainly due to the fast reaction rate of methanol dehydration to DME compared to CO hydrogenation to methanol. The two important characteristics of the metallic surface area of copper and the amount of acidic sites are well correlated with the intrinsic catalytic activity on this consecutive reaction. The intrinsic activity for the direct DME synthesis from syngas on bifunctional catalysts initially decreases and maintains at constant value with the increase of the values of the copper surface area multiplied by the amount of acidic site.

Transformations of monoterpene hydrocarbons on ferrierite type zeolites

Transformations of α-pinene and limonene over hydrogen forms of commercial ferrierite type zeolites of different origin (Tosoh Corp. and Zeolyst Intern.) have been studied in the liquid phase at 313–363K. The catalysts were characterized by XRD, sorption of nitrogen, scanning electron microscopy, FTIR and 27Al &1H MAS NMR. The concentration of Brønsted acid sites has been determined by 1H MAS NMR and FTIR quantitative measurements, while their strength was estimated by adsorption of CO. The liquid-phase isomerization of α-pinene proceeds smoothly on the two zeolite catalysts, and the initial reaction rates have been compared. Camphene and limonene were the main products, while the selectivity to these hydrocarbons differed. Isomerization of pure limonene was also studied, showing large difference in activity over the two ferrierite catalysts. The selectivity of α-pinene transformations has been rationalized in terms of retarded consecutive isomerization of limonene over the zeolite from Zeolyst.

Influence of Al Distribution and Defects Concentration of Ferrierite Catalysts Synthesized From Na-Free Gels in the Skeletal Isomerization of n-Butene

The skeletal isomerization of n-butenes to isobutene has been carried out over ferrierite catalysts (Si/Al ~ 15) containing different acid sites distribution and different amount of defects. The zeolite crystals were synthesized under hydrothermal conditions in fluoride medium in the absence of alkaline cations by using suitable combinations of structure directing agents. Template-driven low density of acid sites in 10-membered-ring channels enhances the isobutene selectivity and decreases catalyst deactivation. The presence of high amount of silanol groups and Lewis acid sites increases the yields of by-products and catalysts decay.

Haldor Topsoe in pilot venture to make DME from biomass

The synthesis of dimethyl ether (DME) from a model gas mixture of biomass-derived syngas has been investigated on the composite catalysts, Cu–ZnO–Al2O3/Zr-modified zeolites (Ferrierite, ZSM-5 and Y). The composite catalysts were synthesized by the coprecipitation of Cu–Zn–Al precursors in the slurry of Zr-modified zeolites. The composite catalyst prepared from Zr–ferrierite showed stable activity and the best DME selectivity. Apart from the easy reducibility of Cu species, the presence of appropriate acid sites of required strength for methanol dehydration is proposed to be the reason for the superior performance of Cu–ZnO–Al2O3/Zr–Ferrierite catalyst.

Dimethyl ether synthesis from syngas over the composite catalysts of Cu–ZnO–Al2O3/Zr-modified zeolites

Abstract The synthesis of dimethyl ether (DME) from a model gas mixture of biomass-derived syngas has been investigated on the composite catalysts, Cu–ZnO–Al 2 O 3 /Zr-modified zeolites (Ferrierite, ZSM-5 and Y). The composite catalysts were synthesized by the coprecipitation of Cu–Zn–Al precursors in the slurry of Zr-modified zeolites. The composite catalyst prepared from Zr–ferrierite showed stable activity and the best DME selectivity. Apart from the easy reducibility of Cu species, the presence of appropriate acid sites of required strength for methanol dehydration is proposed to be the reason for the superior performance of Cu–ZnO–Al 2 O 3 /Zr–Ferrierite catalyst.

Methanol interaction with NO 2: An attempt to identify intermediate compounds in CH 4-SCR of NO with Co/Pd-HFER catalyst

The objective of this work is the study of fundamental common aspects of NO x catalytic reduction over a Co/Pd-HFER zeolite catalyst, using methanol or methane as reducing agent. Temperature Programmed Surface Reaction (TPSR) studies were performed with reactant mixtures comprising NO 2 and one of the reducing agents. The formation of formaldehyde was detected in both studied reactions (NO 2–CH 4 and NO 2–CH 3OH) in the temperature range between 100 and 220 °C. At higher temperature, when the NO x reduction process effectively begins, formaldehyde starts to be consumed. Using methanol as reducing agent, nitromethane and nitrosomethane, are detected. At 300 °C these species are consumed and cyanides and iso-cyanides formation occurs. On the contrary, with methane, these last species were not detected; however, there are strong evidences for CH 3NO and CH 3NO 2 formation. Thus, using methanol or methane, similar phenomena were detected. In both cases, common intermediary species seem to play an important role in the NO x reduction process to N 2. These results suggest that methanol can be considered as a reaction intermediate species in the mechanism of the reduction of NO 2 with methane, over cobalt/palladium-based ferrierite catalysts.

Evolution of Light Hydrocarbons from a Coked Ferrierite Catalyst during Temperature-Programmed Gasification

The evolution of light hydrocarbons during temperature-programmed gasification with helium (TPHe) of a coked ferrierite catalyst was studied to gain information on partial coke removal by heat treatment under inert flow. The catalyst had been deactivated in the skeletal isomerization of alkenes. Characterization by DRIFTS, GC−MS, and 13C CPMAS NMR revealed that the coke contained two- and three-ring aromatic hydrocarbons, as well as polyaromatics. Evolution predominantly of C2−C5 hydrocarbons was observed during TPHe between 200 and 500 °C. The main components were propene and ethene. The carbon content of the catalyst dropped from 4.3 to 3.5 wt % during TPHe. Kinetic models suitable for the purpose of designing a coke removal unit were derived for the evolution of carbon fractions between C2 and C5 from the ferrierite zeolite. The results of the kinetic modeling suggest that one or several bimolecular reactions are relevant in the formation of light hydrocarbons from coke.

Trimerization of isobutene over zeolite catalysts: Remarkable performance over a ferrierite zeolite

Abstract Oligomerization of isobutene has been investigated using several zeolites in order to produce triisobutenes that are useful chemical feedstocks for heavy alkylates and neo-acids. Stable isobutene conversion and high selectivity for trimers are obtained over a ferrierite zeolite at high temperature and low space velocity. Trimers selectivity increases with increasing isobutene conversion. Isobutene is quantitatively oligomerized over a ferrierite catalyst with selectivity for trimers higher than 60% up to 50 h at high isobutene WHSV of 10 h −1 . Moreover, a deactivated catalyst can be regenerated easily by calcining in flowing air. The ferrierite zeolite is one of the potential catalysts for the isobutene trimerization showing high stability, quantitative conversion, high selectivity and easy regeneration.

CH 4-SCR of NO over Co and Pd ferrierite catalysts: Effect of preparation on catalytic performance

Selective catalytic reduction of NO with methane (CH 4-SCR) in the presence of oxygen excess and water vapour was studied over two bimetallic cobalt/palladium-based FER catalysts, which differ on the order of introduction of metal ions. H 2-TPR and UV–vis analysis showed that the simple change in the order of addition of metals to catalyst, gives rise to totally diverse species (Co 2+ ions, Co oxides, Co-oxo cations and Pd species) both in type and quantity but also in location within zeolite framework. Experiments of TPD and TPSR of NO and NO 2 provided important information to establish a relation between the various active sites formed on both catalysts and their function in the reaction mechanism. The importance of NO 2 in the mechanism of NO reaction with CH 4 and O 2 was explored and the catalyst with a higher capacity to retain adsorbed NO 2 is the less active for deNO x . The preparation of a bimetallic catalyst active for NO reduction must provide the proximity between Co and Pd species, and the presence of Co-oxo cations together with palladium species seem to be essential. Furthermore, a suitable amount of cobalt oxides must exist in order to originate NO 2 that is the main reaction intermediate. Nevertheless, an excessive amount of these Co species can lead to an increase of adsorbed NO 2, which reduces the rate of the reaction of some of the mechanism steps.

Kinetic Modeling of Coke Oxidation of a Ferrierite Catalyst

Kinetic models describing coke oxidation were derived for purposes of designing a catalyst regeneration unit and to gain information on coke oxidation kinetics. The coke was formed during an alkene skeletal isomerization reaction on a ferrierite catalyst. Experiments were performed according to the temperature-programmed oxidation technique at several oxygen concentrations and heating rates. The parameters of the models were estimated by nonlinear regression. A power-law model with parametrized order of oxygen concentration described the experimental results adequately. Three other successful models, which were based on assumed reaction mechanisms, shared two main characteristics: the formation of a reactive oxygen intermediate in a fast equilibrium reaction, and the formation of CO and CO2 from one or more common precursors. All estimated parameters of the models were in a physically meaningful range.

Modelling of carbon and hydrogen oxidation kinetics of a coked ferrierite catalyst

The hydrocarbons in an alkene skeletal isomerisation process cause catalyst deactivation by forming coke that blocks the active sites. Oxidation of the coke is carried out in a regeneration unit to reactivate the catalyst. A kinetic model for the combustion is essential for purposes of designing the regeneration unit, since the highly exothermic oxidation releases heat that can damage the catalyst and the unit. Kinetic models were derived and tested by non-linear regression against the results of temperature programmed oxidation experiments with a coked ferrierite catalyst. Two methods for the measurement of carbon oxides in the reactor outflow – a direct analysis by mass spectrometry and an indirect analysis by a methanation method – were compared, and both were found appropriate. The determination of water by mass spectrometry was found adequate. The derived models cover the oxidation of both coke carbon and hydrogen. A power law model with an oxygen concentration order of half in carbon oxidation and zero order in hydrogen oxidation described the experimental results well. Two other models, in which active intermediate species are formed in fast equilibrium reactions, performed as well as the power law model. The estimated parameters of the models were in the physically meaningful range.

Dynamic Modeling of Catalyst Deactivation in Fixed-Bed Reactors: Skeletal Isomerization of 1-Pentene on Ferrierite

In this work, we have derived a general dynamic model for a fixed-bed reactor involving combined reaction kinetics and deactivation kinetics. Catalyst deactivation was treated as a surface reaction among the other reactions. The evolved system of partial differential equations (PDEs) was solved numerically by the method of lines. Several rival deactivation mechanisms for ferrierite catalyst in skeletal isomerization of 1-pentene were investigated. The model assuming two adsorbed n-pentene molecules as surface species forming coke explained the experimental results best.