Dealuminated Beta zeolite reverses Ostwald ripening for durable copper nanoparticle catalysts.

Copper nanoparticle-based catalysts have been extensively applied in industry, but the nanoparticles tend to sinter into larger ones in the chemical atmospheres, which is detrimental to catalyst performance. In this work, we used dealuminated Beta zeolite to support copper nanoparticles (Cu/Beta-deAl) and showed that these particles become smaller in methanol vapor at 200°C, decreasing from ~5.6 to ~2.4 nanometers in diameter, which is opposite to the general sintering phenomenon. A reverse ripening process was discovered, whereby migratable copper sites activated by methanol were trapped by silanol nests and the copper species in the nests acted as new nucleation sites for the formation of small nanoparticles. This feature reversed the general sintering channel, resulting in robust catalysts for dimethyl oxalate hydrogenation performed with supported copper nanoparticles for use in industry.

Physical regulation of copper catalyst with a hydrophobic promoter for enhancing CO2 hydrogenation to methanol.

The hydrogenation of CO2 to methanol, which is restricted by water products, requires a selective removal of water from the reaction system. Here, we show that physically combining hydrophobic polydivinylbenzene with a copper catalyst supported by silica can increase methanol production and CO2 conversion. Mechanistic investigation reveals that the hydrophobic promoter could hinder the oxidation of copper surface by water, maintaining a small fraction of metallic copper species on the copper surface with abundant Cuδ+, resulting in high activity for the hydrogenation. Such a physically mixed catalyst survives the continuous test for 100 h owing to the thermal stability of the polydivinylbenzene promoter.

Fischer-Tropsch synthesis to olefins boosted by MFI zeolite nanosheets.

Catalytic reactions are severely restricted by the strong adsorption of product molecules on the catalyst surface, where promoting desorption of the product and hindering its re-adsorption benefit the formation of free sites on the catalyst surface for continuous substrate conversion1,2. A solution to this issue is constructing a robust nanochannel for the rapid escape of products. We demonstrate here that MFI zeolite crystals with a short b-axis of 90-110 nm and a finely controllable microporous environment can effectively boost the Fischer-Tropsch synthesis to olefins by shipping the olefin molecules. The ferric carbide catalyst (Na-FeCx) physically mixed with a zeolite promoter exhibited a CO conversion of 82.5% with an olefin selectivity of 72.0% at the low temperature of 260 °C. By contrast, Na-FeCx alone without the zeolite promoter is poorly active under equivalent conditions, and shows the significantly improved olefin productivity achieved through the zeolite promoter. These results show that the well-designed zeolite, as a promising promoter, significantly boosts Fischer-Tropsch synthesis to olefins by accelerating escape of the product from the catalyst surface.

Physical mixing of a catalyst and a hydrophobic polymer promotes CO hydrogenation through dehydration.

In many reactions restricted by water, selective removal of water from the reaction system is critical and usually requires a membrane reactor. We found that a simple physical mixture of hydrophobic poly(divinylbenzene) with cobalt-manganese carbide could modulate a local environment of catalysts for rapidly shipping water product in syngas conversion. We were able to shift the water-sorption equilibrium on the catalyst surface, leading to a greater proportion of free surface that in turn raised the rate of syngas conversion by nearly a factor of 2. The carbon monoxide conversion reached 63.5%, and 71.4% of the hydrocarbon products were light olefins at 250°C, outperforming poly(divinylbenzene)-free catalyst under equivalent reaction conditions. The physically mixed CoMn carbide/poly(divinylbenzene) catalyst was durable in the continuous test for 120 hours.

Metal 3D printing technology for functional integration of catalytic system.

Mechanical properties and geometries of printed products have been extensively studied in metal 3D printing. However, chemical properties and catalytic functions, introduced by metal 3D printing itself, are rarely mentioned. Here we show that metal 3D printing products themselves can simultaneously serve as chemical reactors and catalysts (denoted as self-catalytic reactor or SCR) for direct conversion of C1 molecules (including CO, CO2 and CH4) into high value-added chemicals. The Fe-SCR and Co-SCR successfully catalyze synthesis of liquid fuel from Fischer-Tropsch synthesis and CO2 hydrogenation; the Ni-SCR efficiently produces syngas (CO/H2) by CO2 reforming of CH4. Further, the Co-SCR geometrical studies indicate that metal 3D printing itself can establish multiple control functions to tune the catalytic product distribution. The present work provides a simple and low-cost manufacturing method to realize functional integration of catalyst and reactor, and will facilitate the developments of chemical synthesis and 3D printing technology.

A Well-Defined Core-Shell-Structured Capsule Catalyst for Direct Conversion of CO2 into Liquefied Petroleum Gas.

A Pd/SiO2 @S1@H-ZSM-5 capsule catalyst (Pd/SiO2 -SZ) is fabricated through a dual-layer crystal growth method with an auxiliary hydrothermal reaction. The catalyst exhibits excellent selectivity to liquefied petroleum gas (LPG) in CO2 hydrogenation reactions, which is attributed to the tandem reactions of methanol synthesis on the Pd/SiO2 core catalyst and methanol dehydration to hydrocarbons on the H-ZSM-5 shell. The Pd/SiO2 -SZ capsule catalyst has a similar mesoporous structure, narrow range of Pd particles size distribution, and consistent reduction characteristics to the Pd/SiO2 core catalyst. It maintains the physical and chemical properties of the core catalyst throughout the H-ZSM-5 shell synthesis process. Energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy results reveal that the H-ZSM-5 zeolite shell completely encapsulates the Pd/SiO2 core catalyst. Compared with the crushed capsule catalyst (Pd/SiO2 -SZP), the well-defined-structured Pd/SiO2 -SZ catalyst has a much higher LPG selectivity of 33.6 %, owing to the well-matched reactions at the Pd/SiO2 core and H-ZSM-5 shell.

Direct and Oriented Conversion of CO2 into Value-Added Aromatics.

The oriented conversion of CO2 into target high-value chemicals is an effective way to reduce carbon emissions, but still presents a challenge. In this communication, we report the oriented conversion of CO2 into value-added aromatics, especially para-xylene, in a single pass by combining core-shell structured Zn-doped H-ZSM-5 (Zn-ZSM-5@SiO2 ) and a Cr2 O3 component. Through precise regulation of the acidity of Zn-ZSM-5@SiO2 , high para-xylene selectivity (38.7 % in the total products) at a CO2 conversion of 22.1 % was achieved. Furthermore, a CO2 -assisted effect in the synthesis of aromatics during the tandem process has been clarified through a control experiment. The CO2 reactant can act as a hydrogen acceptor to accelerate the dehydrogenation of alkenes, intermediates in the synthesis of aromatics, thereby increasing the driving force towards aromatics in the tandem reaction process.

A brand new zeolite catalyst for carbonylation reaction.

Carbonylation is an effective way to introduce carbonyl groups into organic chemicals. However, the known zeolite candidates for carbonylation are very few. Here, we discovered a new zeolite EU-12 that shows excellent catalytic performance for carbonylation reactions, inserting carbonyl groups into dimethyl ether (DME) to produce methyl acetate (MA). This finding adds a brand new zeolite to the solid catalyst family for carbonylation reaction.

Dynamic Characteristics of Sequential Acute Exacerbations and Risk Windows in AECOPD Rats Induced by Cigarette-Smoke and Exposure to Klebsiella pneumoniae.

The risk-window (RW) of chronic obstructive pulmonary disease (COPD) is a period after an acute exacerbation (AE) but before the following stable phase, in which exacerbations are easy to relapse. We established a sequential COPD-AE-RW rat model by cigarette-smoke and bacterial exposures in the first 8 weeks, and was challenged with Klebsiella pneumonia to mimic an AE on Day 1 of week 9, and found that body temperature, white blood cell, neutrophils, serum amyloid A (SAA) and C-reactive protein (CRP) increased in AECOPD rats 24 h after challenge, and declined in 3-6 d, while lung function declined in 48 h, and recovered in 7-16 d. When sacrificed, pulmonary forced expiratory volume (FEV)100 and FEV300 decreased, while elevated bronchoalveolar lavage fluid (BALF) neutrophils and marked airway inflammation, remodeling and emphysema were observed. Sequential COPD-AE-RW rat model was established successfully and AE phase lasts for approximately 5-7 d, followed by a 10-d around risk-window.

Sequential Treatments with Tongsai and Bufei Yishen Granules Reduce Inflammation and Improve Pulmonary Function in Acute Exacerbation-Risk Window of Chronic Obstructive Pulmonary Disease in Rats.

Background. Sequential treatments of Chinese medicines for acute exacerbation of chronic obstructive pulmonary disease (AECOPD) risk window (RW) have benefits for preventing reoccurrences of AEs; however, the effects on pulmonary function, pulmonary, and systemic inflammatory biomarkers remain unclear. Methods. Cigarette-smoke/bacterial infections induced rats were randomized into Control, COPD, AECOPD, Tongsai Granule/normal saline (TSG/NS), moxifloxacin + salbutamol/NS (MXF+STL/NS), TSG/Bufei Yishen Granule (BYG), MXF+STL/STL, and TSG+MXF+STL/BYG+STL groups and given corresponding medicine(s) in AE- and/or RW phase. Body temperature, pulmonary function, blood cytology, serum amyloid A (SAA) and C-reactive protein (CRP), pulmonary histomorphology and myeloperoxidase (MPO), polymorphonuclear (PMN) elastase, interleukins IL-1ß, IL-6, and IL-10, and tumor necrosis factor- (TNF-) α expressions were determined. Results. Body temperature, inflammatory cells and cytokines, SAA, CRP, and pulmonary impairment were higher in AECOPD rats than stable COPD, while pulmonary function declined and recovered to COPD level in 14-18 days. All biomarkers were improved in treated groups with shorter recovery times of 4-10 days, especially in TSG+MXF+STL/BYG+STL group. Conclusion. Sequential treatments with Tongsai and Bufei Yishen Granules, during AECOPD-RW periods, can reduce inflammatory response and improve pulmonary function and shorten the recovery courses of AEs, especially the integrated Chinese and Western medicines.