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Cu‐exchanged chabazite zeolite is the state‐of‐the‐art used on‐board catalyst for NOx selective reduction by ammonium (NH3‐SCR), and the zeolite is currently generated in the presence of N,N,N‐trimethyl‐1‐adamantylammonium hydroxide, serving as organic structure‐directing agent (OSDA). The expensiveness of this OSDA increases the catalyst production cost, while its low degradability brings about environmental concerns in post treatment of waste water. Here, a new type OSDA, 1‐(1‐methylpropyl)‐4‐aza‐1‐azoniabicyclo[2.2.2]octane hydroxide, is proposed to direct Faujasite‐to‐Chabazite inter‐zeolite conversion and generate chabazite with Si/Al ratio up to 7.2. The obtained zeolite possesses high hydrothermal stability for the high crystallinity, siliceous framework and low concentrations of Si(2Si, 2Al) sites. The Cu‐form catalyst exhibits better catalytic performance in standard NH3‐SCR process for the tiny crystallite size (35–258 nm) and formation of highly dispersed copper sites. The synthesis offers a new type of OSDA to fabricate zeolites and expands the toolkit to regulate their physicochemical properties. [ABSTRACT FROM AUTHOR]

Commercial SSZ‐13 zeolite with different n(Si)/n(Al) ratios and from different suppliers were subjected to a post‐synthetic treatment in order to create mesopores of up to 15 nm. Furthermore, the materials were modified with copper ions and thoroughly physico‐chemically characterized. The modified textural properties varied the nature of copper species, and thus, activity in the selective catalytic reduction of NOx with ammonia (NH3‐SCR‐DeNOx). Pulsed‐field gradient nuclear magnetic resonance (PFG‐NMR) studies with hexane as probe liquid revealed improved intracrystalline diffusion for some Cu‐containing SSZ‐13 materials. The NH3‐SCR‐DeNOx pathways are verified via in situ DR UV‐Vis, in situ FT‐IR and EPR, temperature‐programmed studies as well as SSITKA studies that provide a mechanistic understanding of the reaction. Kinetic modelling results demonstrate the highest NH3‐SCR‐DeNOx reaction rates and up to 20 % lower energy barriers with n(Si)/n(Al) ratio of 6.5 for all modified forms (i. e., (NH4)Cu‐SSZ‐13_6.5 and Cu‐SSZ‐13_6.5_NaOH/0.1) and cause only negligible parasitic ammonia oxidation. The modelling of the stop‐flow experiments further demonstrates that the SCR pathway via the HONO surface intermediate is present but barely contributes to the overall NO conversion compared to the dominant path between adsorbed NH3 and NO from the gas phase. [ABSTRACT FROM AUTHOR]

ERI and SSZ-13 were subjected to post-synthetic treatments (depending on the zeolite topology) to create micro-/mesoporous materials. The results in terms of NH3-SCR-DeNOx show that the applied treatments improved the catalytic activity of the Cu-containing ERI-based materials; however, the NO conversion did not vary for the different materials treated with NaOH or NaOH/HNO3. For the micro-/mesoporous Cu-containing SSZ-13, a lower NO conversion in NH3-SCR-DeNOx was observed. Thus, our findings challenge the current paradigm of enhanced activity of micro-/mesoporous catalysts in NH3-SCR-DeNOx. The modification of the supports results in the presence of different amounts and kinds of copper species (especially isolated Cu2+ and aggregated Cu species) in the case of ERI- and SSZ-13-based samples. The present copper species further differentiate the formation of reactive reaction intermediates. Our studies show that besides the μ-η2,η2-peroxo dicopper(II) complexes (verified by in situ DR UV-Vis spectroscopy), copper nitrates (evidenced by in situ FT-IR spectroscopy) also act as reactive intermediates in these catalytic systems. [ABSTRACT FROM AUTHOR]

Converting CO2 to olefins is an ideal route to achieve carbon neutrality. However, selective hydrogenation to light olefins, especially single‐component olefin, while reducing CH4 formation remains a great challenge. Herein, we developed ZnZrOx/SSZ‐13 tandem catalyst for the highly selective hydrogenation of CO2 to light olefins. This catalyst shows C2=−C4= and propylene selectivity up to 89.4 % and 52 %, respectively, while CH4 is suppressed down to 2 %, and there is no obvious deactivation. It is demonstrated that the isolated moderate Brønsted acid sites (BAS) of SSZ‐13 promotes the rapid conversion of intermediate species derived from ZnZrOx, thereby enhancing the kinetic coupling of the reactions and inhibit the formation of alkanes and improve the light olefins selectivity. Besides, the weaker BAS of SSZ‐13 promote the conversion of intermediates into aromatics with 4–6 methyl groups, which is conducive to the aromatics cycle. Accordingly, more propene can be obtained by elevating the Si/Al ratio of SSZ‐13. This provides an efficient strategy for CO2 hydrogenation to light olefins with high selectivity. [ABSTRACT FROM AUTHOR]

Monoliths manufactured by Direct Ink Writing containing 60% SSZ-13 (SiO2/Al2O3 = 23) and SiO2 with 10% laponite as a binder were investigated as self-standing structured catalysts for NH3-SCR of NOx after a short (4 h) and prolonged (24 h) ion exchange with copper and then compared with pure SSZ-13 exchanged under the same conditions. The catalysts were characterized by morphological (XRD and SEM), textural (BET and pore size distribution), chemical (ICP-MS), red-ox (H2-TPR), and surface (NH3-TPD) analyses. The silica-based binder uniformly covered the SSZ-13 particles, and copper was uniformly distributed as well. The main features of the pure Cu-exchanged SSZ-13 zeolite were preserved in the composite monoliths with a negligible contribution of the binder fraction. NH3-SCR tests, carried out on both monolithic and powdered samples in the temperature range of 70–550 °C, showed that composite monoliths provided very good activity, and that the intrinsic activity of SSZ-13 was enhanced by the hierarchical structure of the composite material. [ABSTRACT FROM AUTHOR]

Aluminosilicate zeolites are widely recognized as an industrially important crystalline microporous material. Among them, small-pore SSZ-13 stands out as an artificial aluminosilicate zeolite with CHA topology. Since its invention in 1985, SSZ-13 zeolite has garnered significant attention in both academia and industry due to its exceptional performance in heterogeneous catalysis, gas adsorption and separation. Modification of its physicochemical properties to meet the diverse requirements of various application scenarios has become a prominent topic in zeolite research. Considerable efforts have been devoted to alleviating the diffusion limitations inherent in micropores by downsizing crystal size or introducing additional mesopores and/or macropores to construct hierarchical structures. Regulating framework Al atoms in isolation or pairing introduces remarkable catalytic or adsorptive diversity into compositionally similar SSZ-13 zeolites. The conventional synthesis of SSZ-13 zeolite, which involves the use of expensive and toxic N,N,N-trimethyl-1-adamantylammonium hydroxide (TMAdaOH) as an organic structure-directing agent (OSDA) and a hydrothermal crystallization process lasting typically more than four days, severely hinders its cost-effective utilization. In response, extensive research endeavors have been dedicated to developing innovative synthetic approaches for SSZ-13 zeolites aimed at greener, more efficient, and economically viable production. This article presents a comprehensive overview of recent research developments in the field of SSZ-13 zeolites, encompassing novel synthetic methods, hierarchical engineering, nanocrystal technology, Al distribution, fast synthesis, and cost reduction techniques, aiming to provide valuable insights and guidance to relevant researchers.

In this study, mechanistic aspects of NO adsorption/desorption over a home-made Pd/SSZ-13 passive NOx adsorber (PNA) catalyst are investigated. Operando FT-IR spectroscopy and microreactor experiments are performed to envisage the performance of the catalyst and the pathway involved in NO adsorption, with particular emphasis to the impact of species such as C3H6 and CO. In the absence of C3H6 and CO, NO is observed to adsorb as nitrosyls (anhydrous and hydrated) over both Pd2+ and Pd+ species, and as nitrates. 80 μmolNOx/gcat (NO/Pd molar ratio of 0.8) are adsorbed. The stability of nitrosyls is higher in comparison to the nitrates in that the former initially dehydrate and further decompose at elevated temperatures (> 300 °C) leading to the evolution of NO. The presence of CO and C3H6 negatively affects the amounts of NO adsorbed (53 and 45 μmolNOx/gcat, respectively) due to the reduction of Pd sites. CO admission to the catalyst forms a variety of carbonyl species over Pd2+, Pd+ and Pd0 sites which upon NO admission are readily displaced and NO is adsorbed as hydrated/anhydrous nitrosyls of Pdn+. The nitrosyls so formed exhibit lower thermal stability in comparison to nitrosyls observed in the absence of CO and decompose below 300 °C. The addition of C3H6 leads to the apparent formation of oxidized species like acetone, acrolein and acetates, besides propylene adsorption. The NO adsorption in the presence of C3H6 leads to the formation of Pdn+(NO)(X) complexes; upon heating the decomposition of this complexes is observed at low temperatures along with propylene and water desorption. Formation of organic nitro-compounds is also observed that decompose at higher temperatures. [ABSTRACT FROM AUTHOR]

DeNOx activity in a NSR–SCR hybrid system of two copper-containing chabazite-type zeolitic catalysts was addressed. A Pt-Ba-K/Al2O3 model catalyst was used as the NSR (NOx storage and reduction) catalyst. For the SCR (selective catalytic reduction) system, two Cu-CHA zeolites were synthesized employing a single hydrothermal synthesis method assisted with ultrasound and incorporating Cu in a 2 wt.%, 2Cu-SAPO-34 and 2Cu-SSZ-13. The prepared catalysts were characterized, and the crystallinity, surface area, pore size, HR-TEM and EDX mapping, coordination of Cu ions and acidity were compared. The NH3 storage capacity of the SCR catalysts was 1890 and 837 μmol NH3·gcat−1 for 2Cu-SAPO-34 and 2Cu-SSZ-13, respectively. DeNOx activity was evaluated for the single NSR system and the double-bed NSR–SCR by employing alternating lean (3%O2) and rich (1%H2) cycles, maintaining a concentration of 600 ppm NO, 1.5% H2O and 0.3% CO2 between 200 and 350 °C. The addition of the SCR system downstream of the NSR catalyst significantly improved NOx conversion mainly at low temperature, maintaining the selectivity to N2 above 80% and reaching values above 90% at 250 °C when the 2Cu-SSZ-13 catalyst was located. The total reduction in the production of NH3 and ~2% of N2O was observed when comparing the NSR–SCR configuration with the single NSR catalyst.

DeNOx activity in a NSR–SCR hybrid system of two copper-containing chabazite-type zeolitic catalysts was addressed. A Pt-Ba-K/Al2O3 model catalyst was used as the NSR (NOx storage and reduction) catalyst. For the SCR (selective catalytic reduction) system, two Cu-CHA zeolites were synthesized employing a single hydrothermal synthesis method assisted with ultrasound and incorporating Cu in a 2 wt.%, 2Cu-SAPO-34 and 2Cu-SSZ-13. The prepared catalysts were characterized, and the crystallinity, surface area, pore size, HR-TEM and EDX mapping, coordination of Cu ions and acidity were compared. The NH3 storage capacity of the SCR catalysts was 1890 and 837 μ mol   NH 3 · g cat − 1 for 2Cu-SAPO-34 and 2Cu-SSZ-13, respectively. DeNOx activity was evaluated for the single NSR system and the double-bed NSR–SCR by employing alternating lean (3%O2) and rich (1%H2) cycles, maintaining a concentration of 600 ppm NO, 1.5% H2O and 0.3% CO2 between 200 and 350 °C. The addition of the SCR system downstream of the NSR catalyst significantly improved NOx conversion mainly at low temperature, maintaining the selectivity to N2 above 80% and reaching values above 90% at 250 °C when the 2Cu-SSZ-13 catalyst was located. The total reduction in the production of NH3 and ~2% of N2O was observed when comparing the NSR–SCR configuration with the single NSR catalyst. [ABSTRACT FROM AUTHOR]

[Display omitted] • Molecular sieve configuration affects the state of existence of Fe species. • Decomposition properties of N 2 O correlate with Fe3+ on the skeleton. • Fe-ZSM-5 has the best low-temperature (200–400 °C) N 2 O decomposition properties. This study systematically investigated the relationship between active species and the direct decomposition of nitrous oxide (N 2 O) over various Fe-based zeolites (Fe-ZSM-5, Fe-SSZ-13, and Fe-Beta) based upon a simulated gas test platform. A comprehensive analysis with XRD, N 2 adsorption–desorption, TEM, UV-Raman, XPS, H 2 -TPR, O 2 -TPD, and NH 3 -TPD was performed for structure and species change to investigate the role of Fe sites and acidity. A series of experiment results revealed a distinct hierarchy in the overall N 2 O decomposition, with Fe-ZSM-5 demonstrating the highest efficacy, achieving exceptional conversion rates exceeding 72 % at 400 °C, followed by Fe-Beta and Fe-SSZ-13. Fe species primarily occurred as isolated Fe3+ of Fe-ZSM-5 catalysts, serving as the main active species in N 2 O decomposition. In contrast, Fe species loaded on Fe-Beta catalysts were predominantly present within the straight pore channels, mostly as low-polymerized Fe x O y clusters, while Fe-SSZ-13 catalysts contained Fe2+, influenced by the cage structure. It should be noted that the unique pore structure of Fe-ZSM-5 facilitated a higher concentration of isolated Fe3+. Additionally, the Fe-ZSM-5 catalysts contained more adsorbed oxygen, which facilitated the desorption of O 2 during the decomposition of N 2 O and promoted the overall decomposition process. The performance of the catalysts in decomposing N 2 O improved with increasing adsorbed oxygen content, consistent with the activity evaluation. [ABSTRACT FROM AUTHOR]

SSZ‐13, small‐pore zeolite with chabazite (CHA) topology, exhibits outstanding performance in gas adsorption‐separation and catalysis. However, most of the studies on SSZ‐13 zeolite are limited to the powder form. In practical application, the SSZ‐13 zeolite should be shaped with a certain amount of inert binder into technical form resulting in reduced performance. Herein, shaped binder‐free SSZ‐13 zeolite was prepared by treating the extruded SSZ‐13/SiO2 sample with amantadine solution under hydrothermal conditions, to crystallize the SiO2 binder into the zeolite phase. The characterization and DFT calculation results point out that the recrystallization of SiO2 binder in shaped SSZ‐13 into zeolite crystal could improve the physical and chemical properties. Enhanced CO2 adsorption capacity and catalysis performance in CO2‐assisted oxidative dehydrogenation of ethane and propane were also found on the shaped binder‐free SSZ‐13 zeolite. [ABSTRACT FROM AUTHOR]

Commercial SSZ-13 zeolite with different n(Si)/n(Al) ratios and from different suppliers were subjected to a post-synthetic treatment in order to create mesopores of up to 15 nm. Furthermore, the materials were modified with copper ions and thoroughly physico-chemically characterized. The modified textural properties varied the nature of copper species, and thus, activity in the selective catalytic reduction of NO x with ammonia (NH 3 -SCR-DeNO x ). Pulsed-field gradient nuclear magnetic resonance (PFG-NMR) studies with hexane as probe liquid revealed improved intracrystalline diffusion for some Cu-containing SSZ-13 materials. The NH 3 -SCR-DeNO x pathways are verified via in situ DR UV-Vis, in situ FT-IR and EPR, temperature-programmed studies as well as SSITKA studies that provide a mechanistic understanding of the reaction. Kinetic modelling results demonstrate the highest NH 3 -SCR-DeNO x reaction rates and up to 20 % lower energy barriers with n(Si)/n(Al) ratio of 6.5 for all modified forms (i. e., (NH 4 )Cu-SSZ-13_6.5 and Cu-SSZ-13_6.5_NaOH/0.1) and cause only negligible parasitic ammonia oxidation. The modelling of the stop-flow experiments further demonstrates that the SCR pathway via the HONO surface intermediate is present but barely contributes to the overall NO conversion compared to the dominant path between adsorbed NH 3 and NO from the gas phase., (© 2024 The Authors. ChemSusChem published by Wiley-VCH GmbH.)

[Display omitted] • Monomeric Cu ions (Z 2 Cu and ZCuOH) do not catalyze dry NO oxidation. • Dehydrated ZCuOH can dimerize to Cu-oxo if diffusion radii of at most 0.50 nm overlap. • Cu-oxo cations come in three pools and catalyze dry NO oxidation at different rates. • Nitrates detected during in situ FTIR are a spectator species. The identification and quantification of multinuclear Cu-oxo cations in Cu-zeolites is a challenge amidst the dynamic nature of Cu ions in Cu-zeolites. Herein, we synthesized Cu-SSZ-13 zeolites containing varying densities of monomeric Cu cations (Z 2 Cu and ZCuOH, where Z represents an anionic site on the z eolite framework). The number of Cu-oxo cations, quantified using carbon monoxide temperature programmed reduction (CO-TPR), quadratically increased with increasing ZCuOH density, evidencing that proximal ZCuOH sites are precursors to Cu-oxo dimers. We also find that dehydrated proximal ZCuOH with overlapping diffusion radii of at most 0.5 nm can form Cu-oxo dimers. CO-TPR also revealed the presence of three distinct pools (i.e types) of Cu-oxo dimers; these pools catalyze dry NO oxidation at different turnover rates, with the fastest pool 2 to 30 times faster than the slowest pool. From reaction kinetics and rate law analysis, we also proposed a cohesive dry NO oxidation mechanism and demonstrated that nitrates detected by in situ FTIR are a spectator species. [ABSTRACT FROM AUTHOR]

SSZ-13 and SSZ-39 zeolites were synthesized, then were with Cu ion-exchanged to obtain catalysts with similar Cu content and tested during NO selective catalytic reduction with NH3 (NH3-SCR), in order to investigate the effect of two zeolites with similar structures in NH3-SCR. Both catalysts were very active in the 150–600 °C temperature range. It was necessary to use high space velocity (520,000 h−1) to properly determine the activity during NH3-SCR of our catalysts in the 150–600 °C temperature range. At higher space velocity, a complete picture of the reactivity of each catalyst was revealed. The 2.5/SSZ-13 catalyst was observed to have a higher NO activity per Cu than 3.7/SZZ-39. The conversion-temperature traces were different, with a "Seagull shape" present in the 3.7/SSZ-39 catalyst. This difference seems to be linked to variations in the Cu exchange level and the distribution of Cu species between both zeolitic structures. The activation energy and preexponential factors calculated assuming a pseudo-first-order reaction during SCR start were also different, presumably reflecting minor variations in the active Cu-zeolite bonding. Measurements by TPD- NH3 gave a similar amount of NH3 adsorbed in both materials (~ 0.14 mmol NH3/g), but the temperature at the maximum desorption rate was different (430 °C-2.5/SSZ-13 and 290 °C-3.7/SSZ-39); this is related to differences in Cu content. Our UV–VIS-NIR data show variations in the distribution of Cu species because of the reaction. Dimeric Cu sites and Cu2+ were significant in both catalysts after the reaction. The Cu content and the structure of the active Cu sites are significant factors determining the activity variations as a function of temperature and in understanding the activity of these small pore zeolites. [ABSTRACT FROM AUTHOR]

Two different seed crystals (K–CHA and nano-scaled SAPO-34) were used to promote the rapid interzeolite conversion of USY and fumed silica to pure SSZ-13 zeolite phase via a grinding route. The results show that both seeds can shorten the crystallization time of SSZ-13 zeolite to 24h, which is much shorter than the syntheses in the absence of seeds. The phase purity, morphology, textural parameters, elemental compositions and acid properties of two typical H–SSZ-13 samples with seeds were analyzed by XRD, SEM, N2 physisorption, EDS and NH3–TPD techniques in detail, and compared with the sample without seeds and a reference sample. The results indicate that the introduction of seeds can effectively modify the acid properties of H–SSZ-13, especially their medium strong acid sites. The methanol-to-olefins (MTO) reaction was employed as a probe to evaluate the catalytic stability of above four H–SSZ-13 catalysts. The results reveal that the catalytic lifetime of the two catalysts using seeds is much longer than that of the one without seeds and the reference sample H–SSZ-13–RS. It was speculated that the appropriate concentration of medium strong acid sites may play a pivotal role in prolonging their catalytic lifetime. Here our findings may throw light on the rational design of long-lifetime H-SSZ-13 catalysts in the MTO reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • SSZ-13 with relatively wide Si/Al can be obtained without seed and extra silica and alumina. • Relatively cheap template DMCHA was effective to convert Y zeolite into SSZ-13. • Mixed Y zeolites can be converted into homogeneous (not mixed) SSZ-13. • SSZ-13 can be very effective in the ethylene-to-propylene (ETP) or acid catalysis. • Moderately siliceous SSZ-13 showed good ETP prrformance than aluminous or siliceous one. SSZ-13 zeolite (CHA structure) with small pore or 8-membered ring has been widely studied in catalysis and adsorption. Even SSZ-13 might be very useful in such applications, the synthesis usually relies on expensive organic templates. In this study, SSZ-13 was obtained, with a relatively inexpensive template, N,N , N -dimethylethylcyclohexylammonium bromide, from conversion of Y zeolites with wide silica/alumina ratios (SARs), especially in the absence of any crystal seed, additional silica and alumina. The obtained SSZ-13 s have relatively wide SAR of 6.9–36.7; and phase-pure SSZ-13 s could also be obtained from mixture of Y zeolites. The obtained SSZ-13 s, in proton form, were applied in ethylene-to-propylene (ETP) reaction, and the SSZ-13 with suitable SAR (18.8) had not only high propylene yield but also stable propylene production compared with other SSZ-13 s, showing the possible application of the SSZ-13 in ETP reaction. [ABSTRACT FROM AUTHOR]

Small-pore zeolites, such as CHA (0.38 nm), have pores that are comparable to the size of CH 4 but larger than the size of CO 2. As a result of the combination of diffusion and adsorption, these membranes are projected to have strong CO 2 /CH 4 selectivity and CO 2 permeance. During this work, SSZ-13 CHA membranes were synthesized, evaluated, and characterized by X-ray Diffraction, Field-Emission Scanning Electron Microscopy, Energy-Dispersive X-ray Spectroscopy, Fourier Transform Infrared Spectroscopy, Solid-State Nuclear Magnetic Resonance, and Thermogravimetric Analysis. Synthesized membranes on the inner surface of single channel alumina supports with a pore size of 200 nm and a length of 105 mm and an active membrane area of ∼17 cm2 showed an ideal permselectivity for CO 2 /CH 4 of 122 (in the single gas permeation measurement) and a CO 2 permeance of 36.1 × 10−7 [mol/(m2 s Pa)] and CO 2 /CH 4 selectivity of 173 and a CO 2 permeance of 6.5 × 10−7 [mol/(m2 s Pa)] for equimolar CO 2 − CH 4 mixture. According to the results, the membranes are capable of separating CO 2 from natural gas and upgrading biogas for industrial purposes. [Display omitted] • SSZ-13 membranes characterized using XRD, ATR-FTIR, FESEM, EDX, Si-NMR. • High CO 2 permeance of ∼3.61 × 106 [mol/(m2sPa)] in single gas permeation. • Ideal selectivity of 20, 122, 540 for CO 2 /N 2 ,/CH 4 and/SF 6. • Mixed gas CO 2 permeance of 9.92 × 10−7 [mol/(m2sPa)] with CO 2 /CH 4 selectivity ∼170. • As-Produced membranes potential for industrial CO 2 separation from biogas. [ABSTRACT FROM AUTHOR]

The stability of industrial catalysts for dry reforming of methane (DRM) reaction is still an urgent challenge. The multifunctional nanocatalyst of SSZ-13 supported Ni/CeO x bimetallic catalysts was successfully fabricated by the impregnation method. The Ni/CeO x species was dispersed highly in the microporous structure of SSZ-13, and the Ni active sites can activate the C-H bond dissociation of CH 4 , while the oxygen vacancy could promote the adsorption and activation of CO 2. The NiCeO x /SSZ-13 catalyst showed excellent catalytic performance for dry reforming of methane, i.e., its conversion of CH 4 and CO 2 were 91 and 94%, and the ratio of H 2 /CO was about 0.88 at 750 °C after 50 h. Based on the results of CH 4 &CO 2 -TPSR and NH 3 -TPD, the synergy effect of NiCeO x species can promote the adsorption and activation of CH 4 and CO 2 , and the coke on the surface during DRM is readily converted to CO by reacting with the surface oxygen from CeO x species, which effectively boost the elimination of carbon deposits. It highlights a new strategy for the fabrication of high-efficient zeolite catalysts for DRM to enhance the utilization of CH 4 and CO 2. [Display omitted] • The multifunctional nanocatalyst of SSZ-13 supported Ni/CeO x bimetallic catalysts was successfully fabricated. • The NiCeO x /SSZ-13 catalyst showed excellent catalytic performance for dry reforming of methane. • The synergy effect of NiCeO x species can promote the adsorption and activation of CH 4 and CO 2. • A new strategy for the fabrication of high-efficient zeolite catalysts for DRM to enhance the utilization of CH 4 and CO 2. [ABSTRACT FROM AUTHOR]

Ir/H-SSZ-13 catalysts were used for methylcyclopentane (MCP) ring-opening (RO) reaction, and exhibit higher yields to RO products than H-ZSM-5, H-USY and Al2O3 supported Ir catalysts. Ir species supported on H-SSZ-13-A (about 200 nm) exhibits higher activity than those on H-SSZ-13-B (about 8 μm) due to its more accessible acid sites. Ir/H-SSZ-13-A gives higher reactivity than Ir/Al2O3, especially in the case of low Ir loading because of the promotion of the strong acid sites located on the external surface of H-SSZ-13-A. This work demonstrates that SSZ-13 supported metal is a potential catalyst for RO reaction.

• Sequential, dual-layer configurations of NO and hydrocarbon trapping compared. • High co-adsorption of NO and n-C 12 H 26 with use of Pd/BEA and Pd/SSZ-13. • n-C 12 H 26 delays NO x desorption to 300 °C. • Dual-layer and Pd/SSZ-13 → Pt + Pd/BEA oxidize NO to NO 2 during desorption. • C 3 H 6 promotes desorption of NO to higher temperatures from bottom SSZ layer. Vehicular emission control catalysts are ineffective in eliminating CO, hydrocarbons, and NO x during engine cold-start when exhaust temperatures are below 200 °C. In this study the performance of coupled low temperature NO x , n -C 12 H 26 (C 12), and C 3 H 6 trapping, release and conversion for a series of model Lean Hydrocarbon NO x Trap (LHCNT) catalysts are examined. Pd and Pt supported on small-pore (SSZ-13) and large-pore (BEA) zeolites are selected based on the performance during transient NO and C 12 uptake, release and conversion experiments. These catalysts are combined into sequential (Pt + Pd/BEA → Pd/SSZ-13; Pd/SSZ-13 → Pt + Pd/BEA) and dual-layer (Pt + Pd/BEA top, Pd/SSZ-13 bottom) configurations in an attempt to improve the trapping and conversion performance. While all three configurations trap between 75 and 100 μmolNO x /g-cat, the Pd/SSZ-13 → Pt + Pd/BEA sequential configuration is most effective in simultaneously trapping C 12 and NO in the presence of H 2 O, resulting in excellent NO and C 12 storage below 100 °C with release and/or conversion at or above 200 °C. For each configuration, C 12 oxidation lights-off below 300 °C and NO oxidation achieves ∼35 % conversion in the absence of C 12. Neither the presence of C 12 nor the order of the sequential configuration has a significant impact on NO uptake. C 12 significantly delays NO and NO 2 desorption to temperatures exceeding 300 °C. The more compact dual-layer catalyst is most effective in forming NO 2 as the release temperature lines up with the maximum NO conversion temperature but traps less C 12 than the sequential configurations. The addition of C 3 H 6 in the feed on the dual-layer catalyst leads to further delay in the NO x desorption as well as increased NO and C 12 conversion at high temperatures. The overall findings provide guidance in the optimizing LHCNT configuration for realistic feeds. [ABSTRACT FROM AUTHOR]

• NO uptake and release and DRIFTS measurements made for 1 % Pd/SSZ-13. • NO uptake/Pd loading ∼ 1 implies completely dispersed Pd cations. • Competitive adsorption of NO and H 2 O results in two regimes of NO uptake. • Reductants CO and C 2 H 4 enhance low temperature NO uptake. • Generation of CO 2 for NO + CO and CH 3 CHO for NO + C 2 H 4 confirms Pd redox. The Passive NOx Adsorber (PNA) is an emerging technology to abate cold-start NOx emissions from lean combustion vehicles. Binding sites on Pd-exchanged zeolites adsorb NO at low temperature (< 150 °C) and release NO and NO 2 at higher temperature, enabling their downstream reduction. The impacts of other exhaust components such as H 2 O, hydrocarbons (HCs) and CO, along with operating conditions including temperature and flowrate must be quantified and understood in order to develop effective PNA materials. We have conducted a systematic set of experiments of the NOx uptake and release features on Pd-exchanged SSZ-13 in the absence and presence of several diesel exhaust components. The NO uptake approaches NO/Pd ∼ 1 for a range of conditions, and along with the generation of NO 2 during NO feed and CO 2 (CH 3 CHO) during NO + CO (NO + C 2 H 4) co-feed, suggests the reduction of well-dispersed Pd cations. The total NO uptake between 50 and 150 °C is nearly constant but occurs in both lower temperature (< ∼120 °C) and higher temperature (>120 °C) regimes, indicating competition of NO uptake with H 2 O. The additions of CO and C 2 H 4 increase the lower temperature uptake and higher temperature release of NO, both features desirable for application. In contrast, H 2 , dodecane, and toluene have a negligible effect on the NO uptake. During NO uptake the co-generation of NO 2 , CO 2 and CH 3 CHO, respectively with reductants NO, CO, and C 2 H 4 , provides evidence for the reduction of Pd2+ in the form of [Pd(OH)]+ bound to zeolitic anionic sites [Al-O-Si]− and/or PdO 2 clusters. Supporting DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) measurements identify several potential surface species that are linked to the multiple NO + NO 2 desorption peaks. Two prospective mechanistic schemes are proposed that are consistent with the uptake/release and DRIFTS data. [ABSTRACT FROM AUTHOR]

• A core–shell structure Cu–Ce–La/SSZ-13@ZSM-5 catalyst was synthesized. • Improved hydrothermal stability was achieved on the core–shell catalyst. • The growth of the shell induces the migration and redistribution of metal ions. • The functionalization of the shell boosts the adsorption of NH 3 and the acid cycle. A core–shell structure Cu–Ce–La/SSZ-13@ZSM-5 catalyst with a Cu–Ce–La/SSZ-13 core and a ZSM-5 shell was first synthesized by a self-assembly method and used for ammonia-selective catalytic reduction (NH 3 -SCR). In comparison with Cu–Ce–La/SSZ-13, Cu–Ce–La/SSZ-13@ZSM-5 with appropriate shell thickness presents better SCR activity and hydrothermal stability. We discovered an ion migration effect during the shell phase assembly process and further proposed that the ion migration effect was induced by the dissolution of the core phase during the growth of the shell. Part of the metal ions were migrated and redistributed during the assembly of the ZSM-5 shell, resulting in the transformation of [Cu(OH)]+–Z to Cu2+–2Z species and the functionalization of the shell phase. The functionalized shell is beneficial for the adsorption and activation of NH 3. The results of an H 2 O resistance test and thermogravimetric analysis confirm that the coating of the hydrophobic shell can effectively improve the hydrothermal stability and H 2 O resistance of core–shell Cu–Ce–La/SSZ-13@ZSM-5. [ABSTRACT FROM AUTHOR]

SSZ-13 zeolite was synthesized using four templates, and the synthesis conditions with choline chloride (CC) as template were optimized by dynamic stirring, fluoride-assisted and seed-assisted synthesis. Because the geometric dimensions of CC dimer (7.21 × 10.72 Å) and CHA cage (7.3 × 12 Å) matched closely, the crystallinity and specific surface area of sample synthesized using CC were higher than those of other samples (except for that of the sample synthesized using TMAdaOH). By adopting three improved methods, SSZ-13 samples with better crystallinity, higher specific surface area and more regular morphology could be synthesized in a shorter time (3–4 days). The sample prepared using fluoride-assisted method could achieve a similar crystallinity to the sample synthesized using TMAdaOH. The corresponding catalyst exhibited the best catalytic performance in the NH3-SCR reaction, with 100% NO conversion from 150 to 550 °C. This performance was attributed to fluoride ions promoting the formation of CC dimers through charge attraction of SiF62−. Furthermore, by synthesis optimization, the more developed pore structure, stronger NH3 adsorption capacity and lower CuO content of Cu-SSZ-13 were also important factors for the improved catalytic performance. [ABSTRACT FROM AUTHOR]

The CHA zeolites were synthesized using coke-free and coke-containing spent MFI zeolites via the steam-assisted dry gel conversion method. The results indicate that the coke within the spent MFI precursor has played a vital role in preventing the crystal structure from collapse in a steam condition with the excess synthesis time of 3 days, but the SSZ-13 obtained from coke-free MFI zeolites suffered from a partial collapse in the same synthetic conditions. These could be attributed to the surrounding of some hydrophobic coke onto the surface of SSZ-13 crystallite during the synthesis. Besides, the sample produced from coke-containing spent MFI had better catalytic stability in methanol to olefins as well. SSZ-13 synthesized from coke free MFI (a, c) and coke containing MFI (b, d). [ABSTRACT FROM AUTHOR]

• Na+ addition promotes low temperature turnover rates of Cu/SSZ-13 catalysts. • Na+ addition adversely influences dispersion of isolated Cu-ions. • Na+ addition adversely influences catalyst hydrothermal stability at high Cu loadings. • Co-cation addition to Cu/SSZ-13 can be used in practical SCR catalysts, however care must be taken to control the extents. • Discussions on quantification of isolated Cu-ions with EPR and H 2 -TPR. A series of Cu/H-SSZ-13 and Cu/Na-SSZ-13 catalysts are synthesized, degreened and hydrothermally aged for use in the standard NH 3 -SCR reaction. Surface area/pore volume and XRD analyses are used to probe the textural properties of the catalysts. H 2 -TPR and EPR are used to quantitatively describe the various Cu species. NH 3 -SCR is carried out at a lower space velocity to probe the light-off behavior, and a higher space velocity to generate data for kinetic analysis. Na+ co-cation addition is found to promote turnover rates of isolated Cu-ions at low reaction temperatures. However, as Cu loadings increase, this promoting effect is compromised by decreases in Cu exchange capacity and hydrothermal stability of the Cu/Na-SSZ-13 catalysts. [ABSTRACT FROM AUTHOR]

SSZ-13, with a unique pore structure and excellent thermal stability, showed a potential application in the adsorption and catalysis industry. In this work, Al(NO3)3 was used as an Al source to study the performance and morphology of the zeolite. The zeolite was prepared with an unconventional process by adding an Al source before the structure-directing agent and base. When inorganic oxygen-containing anions were introduced into the unconventional synthesis system, the crystals of the zeolite conform to the unconventional growth mode. The zeolites with large crystals were assembled from small unit nanocrystals. Extending the reaction time, aging time and adding fluoride ions introduced a multistage pore structure on the surface of the molecular sieve, which improved the CO2 adsorption performance. When aging for 24 h, reaction for 96 h, and the amount of fluorine added was 0.05 (F/Si), the sample had the best hierarchical pore structure. The SSZ-13 molecular sieve with an added amount of 0.1 (F/Si) has the highest CO2 adsorption performance. The adsorption amount was 4.55 mmol/g at 1 bar, which is 20.4% higher than that of zeolite SSZ-13 prepared by the conventional process.

Converting CO 2 to olefins is an ideal route to achieve carbon neutrality. However, selective hydrogenation to light olefins, especially single-component olefin, while reducing CH 4 formation remains a great challenge. Herein, we developed ZnZrO x /SSZ-13 tandem catalyst for the highly selective hydrogenation of CO 2 to light olefins. This catalyst shows C 2 = -C 4 is suppressed down to 2 %, and there is no obvious deactivation. It is demonstrated that the isolated moderate Brønsted acid sites (BAS) of SSZ-13 promotes the rapid conversion of intermediate species derived from ZnZrO = , thereby enhancing the kinetic coupling of the reactions and inhibit the formation of alkanes and improve the light olefins selectivity. Besides, the weaker BAS of SSZ-13 promote the conversion of intermediates into aromatics with 4-6 methyl groups, which is conducive to the aromatics cycle. Accordingly, more propene can be obtained by elevating the Si/Al ratio of SSZ-13. This provides an efficient strategy for CO 4 is suppressed down to 2 %, and there is no obvious deactivation. It is demonstrated that the isolated moderate Brønsted acid sites (BAS) of SSZ-13 promotes the rapid conversion of intermediate species derived from ZnZrO x , thereby enhancing the kinetic coupling of the reactions and inhibit the formation of alkanes and improve the light olefins selectivity. Besides, the weaker BAS of SSZ-13 promote the conversion of intermediates into aromatics with 4-6 methyl groups, which is conducive to the aromatics cycle. Accordingly, more propene can be obtained by elevating the Si/Al ratio of SSZ-13. This provides an efficient strategy for CO 2 hydrogenation to light olefins with high selectivity., (© 2024 Wiley-VCH GmbH.)

High silica SSZ-13 zeolite was synthesized by an efficient and green steam-assisted crystallization (SAC) method under a low alkalinity and low organic templates amount system. The as-prepared samples were characterized by XRD, SEM, N2 adsorption–desorption, TG–DTG and NH3-TPD. The results showed that the SAC method can not only remarkably improve zeolite yield but also enhance the crystallization rate of SSZ-13 zeolite compare to conventional hydrothermal route. Meanwhile, it was also found that the various content of the organic structure directing agent (N,N,N-trimethyladamantammonium hydroxide, TMAdaOH) in the dry gel can adjust flexibly the crystal size, morphology and acidity of samples. The zeolite samples with smaller particles and more strong acidity amount were more likely obtained under the higher TMAdaOH/SiO2 ratio (0.2) condition. In addition, the catalytic evaluation in methanol-to-olefins (MTO) reaction showed that the high silica SSZ-13 catalysts synthesized by SAC method exhibited longer lifetime and comparative selectivity to ethylene and propene than those of the SSZ-13s obtained by conventional hydrothermal route. Thus, the SAC route is believed to be a competitive strategy to synthesize high silica SSZ-13 zeolites with improved MTO catalytic performance. [ABSTRACT FROM AUTHOR]

A systematic approach is described for the fabrication of defect-free high-silica zeolite membranes with CHA (SSZ-13) topology. Home-made hydrothermally-synthesized CHA seeds were coated on porous α-alumina substrates with a pore diameter of 80 nm and by means of a further hydrothermal treatment a zeolite membrane layer was formed. In order to obtain a thin and defect-free zeolite layer, the influence on the final microstructure of seed concentration during coating, coating method (rubbing, dip- or spin-coating) and crystal growth time was investigated. The template removal procedure was optimized to avoid the formation of cracks or defects. For an optimal thermal treatment, using a step-wise temperature increase to 500 °C, the membranes exhibit CO 2 /CH 4 permselectivities of 25–30 with CO 2 permeances of around 2 x 10−7 mol m−2 s−1 Pa−1 at 22 °C and 2 bar of pressure difference. O 2 plasma pre-treatment prior to template removal increased the CO 2 /CH 4 permselectivity to 176, while maintaining the same CO 2 permeance values when no pre-treatment was used. The SF 6 permeances, both at low (22 °C) and high (200 °C) temperatures, were below the detection limit (2 x 10−10 mol m−2 s−1 Pa−1), which in return results in very high N 2 /SF 6 permselectivities of more than 700. • High-silica (SSZ-13) CHA zeolite membranes were fabricated by hydrothermal synthesis. • The optimized template removal method avoids the formation of defects. • Oxygen plasma, used as a pre-treatment, improves CO 2 /CH 4 permselectivity by 570%. • The membranes exhibit very high N 2 /SF 6 permselectivities of more than 700. [ABSTRACT FROM AUTHOR]

Generation of hierarchical zeolites is an effective way to enhance their diffusion-dependent catalytic properties. The fabrication of hierarchical zeolites with enhanced diffusion property, high hydrothermal stability, strong acidity in an inexpensive, facile and efficient way is particularly daunting. Here, a simple synthesis of hierarchical SSZ-13 zeolite in a biphasic water/toluene media under tumbling assisted by organosilane, i.e., trimethoxy[3-(phenylamino)propyl]silane, is proposed. The obtained material with tunable Si/Al from 10 to 30 consists of assembled crystallites of 20–30 nm that construct a hierarchical architecture with mesopores of ca. 7 nm opening to the external facets, and has low defect concentration and preserved strong acidity. Crystallization mechanism is disclosed to obey a non-classic attachment growth of nano building blocks mediated by Pickering emulsion, as organosilane modification changes their surface to be hydrophobic. Such a crystallization pathway has accelerated nucleation process and suppressed the growth of SSZ-13 crystals to micron size. Cu exchanged hierarchical SSZ-13 outperforms the standard sample in typical NH 3 -SCR process in both low and high temperature regimes as a result of enhanced diffusion property, as well as low defect concentrations. The synthesis is a cost-effective method for the generation of hierarchical zeolites mediated by the presence of a liquid/liquid interface, and could inspire more such explorations. Image 10 • A phase-transfer method to generate hierarchical SSZ-13 is presented. • The crystallization follows a Pickering emulsion mediated non-classic oriented assembly pathway. • Cu exchanged SSZ-13 shows superior catalytic NH 3 -SCR property at both high (>623 K) and low (<523 K) temperature. • Catalytic activity is enhanced by hierarchical structure owing to improved gas diffusion. [ABSTRACT FROM AUTHOR]

To study the influence of the preparation method on Cu active sites and the reaction pathway in NO reduction by NH3 over Cu–SSZ-13, three kinds of catalysts (Cu ion-exchanged SSZ-131, one-pot synthesis Cu–SSZ-132, and Ce0.017–Fe0.017/Cu–SSZ-13 [Ce and Fe ion exchange on the basis of Cu–SSZ-132]) were prepared. In situ diffuse reflectance infrared Fourier transform spectroscopy and H2 temperature program reduction were used to study the differences in the reaction pathways and Cu active sites over the three kinds of catalysts. Density functional theory was employed to study the effect of active sites on the reaction pathway. In situ DRIFTS showed that the reaction pathway on Cu–SSZ-131 during NO oxidation was different from that on Cu–SSZ-132 and Ce0.017–Fe0.017/Cu–SSZ-13. The difference was that intermediate NO2 was involved in the selective catalytic reduction reaction on Cu–SSZ-131, whereas NO2 was not found during the reaction process on Cu–SSZ-132 and Ce0.017–Fe0.017/Cu–SSZ-13. H2–TPR studies revealed that the three catalysts had different Cu active sites, which were located in the six-membered ring, eight-membered ring, and CHA cage. On the basis of DFT studies, NO and O2 were more conducive to form nitrate when the Cu species was on the six- and eight-membered rings; by contrast, NO and O2 were more conducive to form NO2 in the cage. These results showed that different preparation methods led to various Cu active sites, and varying Cu active sites could lead to different NO oxidation processes. [ABSTRACT FROM AUTHOR]

Abstract Highly crystalline and pure SSZ-13 zeolite is obtained by interzeolite conversion of zeolite Beta and zeolite L. Zeolite Beta is used without preliminary treatment, while zeolite L is subjected to dealumination in order to reach the Si/Al ratio appropriate for the synthesis of SSZ-13. The formation of SSZ-13 from conventional chemicals is also studied. The crystallization from zeolite precursors is much faster and provides pure and highly crystalline SSZ-13. The improved crystal growth kinetics is attributed to the directing effect of the dissolved Si-O-Al fragments from zeolite Beta and zeolite L frameworks. CHA-type zeolites obtained from dealuminated zeolite L crystallized faster, showed higher crystallinity and more defined crystals morphology in respect to those obtained from zeolite Beta. The dealuminated zeolite L was found to be an outstanding starting material for the crystallization of SSZ-13. Graphical abstract Image 1 Highlights • Zeolite Beta and Zeolite L are used as silica-alumina sources for the synthesis of zeolite SSZ-13 (CHA-type). • Factors controlling the interzeolite conversion of zeolite Beta and zeolite L in SSZ-13 are studied. • SSZ-13 shows higher crystallinity and crystallizes faster from zeolite precursors rather than the conventional gels. • Dealuminated zeolite L is a more efficient initial source for the SSZ-13 synthesis in respect to zeolite Beta. [ABSTRACT FROM AUTHOR]

Abstract SSZ-13 zeolite with a SiO 2 /Al 2 O 3 ratio in the range of 26–183 was synthesized by adding zeolite L in the synthesis gel absent from additional aluminum source, and the effects of SiO 2 /Al 2 O 3 and N,N,N-trimethyladamantammonium hydroxide (TMAdaOH)/SiO 2 ratios on the crystallization were investigated. The crystallization mechanism was studied with X-ray diffraction, Scanning electron microscopy, Fourier transform infrared spectroscopy and 29Si and 27Al MAS NMR spectroscopy techniques. It is shown that the SiO 2 /Al 2 O 3 and TMAdaOH/SiO 2 ratios have a significant effect on the acidity, and thus, the methanol-to-olefins (MTO) performance of SSZ-13. The co-presence of TMAdaOH, NaOH and extra silica source (SiO 2) is necessary for formation of SSZ-13. The crystallization of SSZ-13 occurs by decomposing structure of zeolite L into double six- and four-membered rings that subsequently restructure into CHA topology under the direction of TMAdaOH, and further induce the nucleation and crystal growth. It is noteworthy that the Al species in zeolite L directly transform into those of SSZ-13 without forming monomeric species. The prepared SSZ-13 shows higher catalytic stability and selectivity to ethylene and proplyene than the conventionally synthesized sample from amorphous aluminosilicate gel in MTO reaction. Graphical abstract Image 1 Highlights • LTL hydrothermal conversion into high silica CHA was performed with the TMAdaOH. • The product SSZ-13 zeolite was strongly affected by starting Si/Al and SDA/Si ratio. • The crystallization rate of SSZ-13 from L-added starting gel was distinctly enhanced. • The crystallization mechanism of SSZ-13 from L-added starting gel was discussed. • The obtained SSZ-13 from L-added gel showed enhanced catalysis for MTO reaction. [ABSTRACT FROM AUTHOR]

Abstract Chabazite SSZ-13 has attracted wide attention due to its physiochemical properties and excellent potential as a catalyst for various application. In this study, pure phase SSZ-13 CHA zeolite with wide range of Si/Al ratio has been synthesized in a fluoride-free media by dry gel conversion method where the conversion of SSZ-13 from aluminosilicates precursor gel occurs under water vapor. The difference between products produced by conventional hydrothermal synthesis method and the new method has been investigated and characterized with XRD, SEM, XRF, and N 2 adsorption. Pure SSZ-13 with wide range of Si/Al up to 182 was obtained by dry gel conversion method while pure SSZ-13 with higher Si/Al ratio than 20 with similar starting gel composition could not synthesized by hydrothermal synthesis method. Our work has demonstrated that dry gel conversion method was an effective method to synthesize pure SSZ-13 with a wide range of Si/Al ratio under fluoride media-free condition. Graphical abstract Image 1 Highlights • We performed dry gel conversion synthesis for SSZ-13 under fluoride-free and seed-free condition. • Pure SSZ-13 with high silica (up to Si/Al = 182) was obtained by dry gel conversion under fluoride-free and seed-free condition. • The comparative investigation revealed that dry gel conversion method was an effective method to synthesize pure SSZ-13 with a wide range of Si/Al ratio under fluoride-free and seed-free condition. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Fe addition into Cu/zeolites significantly decreases N 2 O formation. • Fe addition into Cu/zeolites suppresses coking formation. • Fe addition modifies (lowers) dispersion of Cu in zeolites. • The adding of Fe can be applied as a method to fine-tune performance of commercial SCR catalysts. Abstract Cu, Fe and Cu + Fe ion exchanged Beta and SSZ-13 catalysts were prepared by solution ion exchange using commercial NH 4 /Beta, and NH 4 /SSZ-13 that was prepared in-house. To study hydrothermal aging effects, Beta supported catalysts were aged hydrothermally at 700 °C and SSZ-13 supported catalysts were aged at 750 °C. In order to reveal the effects of Fe addition in the co-exchanged catalysts, these catalysts were characterized by means of powder X-ray diffraction (XRD), N 2 adsorption-desorption, electron paramagnetic resonance (EPR), 27Al-nuclear magnetic resonance (27Al-NMR) and propylene coking followed with temperature programmed reaction (TPR), and further tested with standard NH 3 -SCR with and without the presence of propylene. Collectively, the catalyst characterizations and reaction testing indicated minor beneficial effects of Fe addition in Cu,Fe/Beta, where NH 3 -SCR activity, N 2 selectivity and hydrothermal stability were all slightly improved. In contrast, Fe addition did not show apparent beneficial effects in low-temperature SCR for the Cu,Fe/SSZ-13 case. At elevated reaction temperatures, however, the presence of Fe indeed considerably improved NO conversion and N 2 selectivity for the hydrothermally aged Cu,Fe/SSZ-13 catalyst in the presence of propylene. [ABSTRACT FROM AUTHOR]

• Chloromethane-to-olefin reaction was investigated using metal oxide-impregnated H-SSZ-13. • SnO 2 -loaded H-SSZ-13 zeolite achieved the highest selectivity for light olefins (>85%). • Controlled SnO 2 loading affected acidity, CH 3 Cl affinity, and formation of aromatic species. • CH 3 Cl conversion, selectivity, coke formation, and lifetime were changed systematically. • Catalysis descriptors clarified the origin of different catalytic performances. The conversion of chloromethane (CH 3 Cl) to olefin (CMTO) is an energy-efficient C 1 -molecular reaction that utilizes CH 3 Cl as a reactive C 1 resource to produce C 2 –C 4 light olefins. Despite its potential, enhancing the activity, olefin selectivity, and catalyst lifetime remain critical challenges in attaining the industrial standard established by the methanol-to-olefin (MTO) reaction. To address these challenges, we synthesized a range of metal oxide-impregnated small-pore H-SSZ-13 zeolites, controlling the type and loading of metal oxide, to investigate their effects on CH 3 Cl conversion, light olefin selectivity, and catalyst lifetime. Our findings revealed that impregnation of SnO 2 at a given metal oxide loading resulted in the highest olefin selectivity (>85%). The variation in SnO 2 loading controlled the surface acidity, which influenced the affinity of CH 3 Cl and led to a systematic change in reaction pathways, governing CH 3 Cl conversion, olefin selectivity, and catalyst lifetime. Through our analysis of the structure–performance relationships, we elucidated the underlying catalyst promotion by SnO 2 impregnation and proposed a reaction process based on the hydrocarbon pool mechanism that systematically controlled selectivity in C 2 –C 4 olefins. These insights provide a robust framework for the design of novel catalysts that offer superior performance in the CMTO reaction. [ABSTRACT FROM AUTHOR]

Because of its unique eight-membered ring pore structure and the arrangement of cations in its structure, the SSZ-13 molecular sieve has a higher affinity for CO2 than other gases, meaning it has attracted more attention than other porous materials for CO2 adsorption. However, the expensive template and long preparation time limits the industrial production of SSZ-13. In this work, a hollow structure was successfully introduced into the nanosized SSZ-13 molecular sieve with ultrasonic treatment. The effects of the amount of seed added and the ultrasonic time on the structure were investigated. When the amount of seed added was 0.5 wt.% and the ultrasonic time was 60 min, the sample showed a hollow cubic crystal with a diameter of about 50 nm. The specific surface area reached 791.50 m2/g, and the mesoporous ratio was 66.3%. The samples were tested for CO2 adsorption performance at 298 K. It was found that the hollow sample prepared in this work has higher CO2 adsorption capacity compared with the SSZ-13 zeolite prepared with conventional methods. When the adsorption pressure was 0.27 bar, the adsorption amount reached 2.53 mmol/g. The hollow SSZ-13 molecular sieve reached a CO2 adsorption capacity of 4.24 mmol/g at 1 bar.