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A two-stage catalytic membrane reactor (CMR) that couples CO2splitting with methane oxidation reactions was constructed based on an oxygen-permeable perovskite asymmetric membrane. The asymmetric membrane comprises a dense SrFe0.9Ta0.1O3-δ(SFT) separation layer and a porous Sr0.9(Fe0.9Ta0.1)0.9Cu0.1O3-δ(SFTC) catalytic layer. In the first stage reactor, a CO2splitting reaction (CDS: 2CO2→ 2CO + O2) occurs at the SFTC catalytic layer. Subsequently, the O2product is selectively extracted through the SFT separation layer to the permeated side for the methane combustion reaction (MCR), which provides an extremely low oxygen partial pressure to enhance the oxygen extraction. In the second stage, a Sr0.9(Fe0.9Ta0.1)0.9Ni0.1O3-δ(SFTN) catalyst is employed to reform the products derived from MCR. The two-stage CMR design results in a remarkable 35.4% CO2conversion for CDS at 900 °C. The two-stage CMR was extended to a hollow fiber configuration combining with solar irradiation. The solar-assisted two-stage CMR can operate stably for over 50 h with a high hydrogen yield of 18.1 mL min−1cm−2. These results provide a novel strategy for reducing CO2emissions, suggesting potential avenues for the design of the high-performance CMRs and catalysts based on perovskite oxides in the future.

Background: Grazing exclusion is a practical approach to restore vegetation in degraded grasslands and enhance soil organic carbon (SOC) sequestration. However, the dynamics and drivers of SOC in grasslands after grazing exclusion have not been well documented, especially in ecosystems with cold climates. Methods: Here, we established 14 paired treatments (grazing exclusion vs. free-grazing) along a 600-km transect in the northeastern zone of the Qinghai-Tibet Plateau. After six years, we analyzed vegetation biomass dynamics and measured the soil physicochemical properties and organic C concentration across three depths (0–10, 10–20, and 20–30 cm). Results: Grazing exclusion significantly increased above- and belowground biomass (139.85% and 43.30%, respectively), pH (1.38%), total phosphorus (3.29%), nitrate nitrogen (18.03%), and ammonium nitrogen (17.81%), but significantly decreased soil bulk density (2.43%) and clay content (10.49%), particularly in 0–30 cm. Specifically, SOC concentrations positively responded to grazing exclusion (0–10 cm) in 9 of the 14 sites evaluated. The effects of grazing exclusion on SOC concentrations were significantly higher in areas with a mean annual temperature (MAT) below 0 °C compared to those in sites with a high MAT (> 0 °C). The SOC concentrations significantly correlated with the mean annual precipitation (MAP) in both treatments, but these correlations diminished with increasing soil depth. Ridge regression analysis showed that soil chemical properties (e.g., total nitrogen and phosphorus) positively influenced SOC accumulation, while MAT negatively influenced it after grazing exclusion. Path analysis further revealed that MAT indirectly regulated SOC dynamics via soil chemical properties. Conclusions: Our study highlights that grazing exclusion results in an asynchronous SOC and plant biomass accumulation and may be more beneficial for SOC sequestration in Qinghai-Tibet Plateau grasslands with lower temperatures. Also, humid climates promote SOC concentration in alpine grasslands. These results could help develop management practices and policies that promote sustainable grassland management.

Catalytic membrane reactors (CMRs), which synergistically carry out separations and reactions, are expected to become a green and sustainable technology in chemical engineering. The use of ceramic membranes in CMRs is being widely considered because it permits reactions and separations to be carried out under harsh conditions in terms of both temperature and the chemical environment. This article presents the two most important types of CMRs: those based on dense mixed-conducting membranes for gas separation, and those based on porous ceramic membranes for heterogeneous catalytic processes. New developments in and innovative uses of both types of CMRs over the last decade are presented, along with an overview of our recent work in this field. Membrane reactor design, fabrication, and applications related to energy and environmental areas are highlighted. First, the configuration of membranes and membrane reactors are introduced for each of type of membrane reactor. Next, taking typical catalytic reactions as model systems, the design and optimization of CMRs are illustrated. Finally, challenges and difficulties in the process of industrializing the two types of CMRs are addressed, and a view of the future is outlined.

•CO2capture capacity of a HFAU exceeded that of a PBAU using an equal mass of CaO•HFAU-based system studied was 92% smaller and 23% cheaper than PBAU-based system•The sorbent-loading inside a HFAU was optimised for the first time•By optimising the sorbent-loading, performance was maximised while costs were saved

Over the past decades, fossil fuel combustion has emitted large quantities of CO2into the atmosphere, resulting in global climate change. Nowadays, it’s considered a feasible strategy to capture CO2from some significant point sources. Three main strategies have been developed, namely post-combustion, pre-combustion, and oxy-fuel combustion. Recent research indicates that the membrane technology for CO2capture has become competitive compared with conventional technologies because of the improved separation performance in materials and process designs. This paper mainly reviews the progress and breakthroughs of membrane materials for the three gas separation systems corresponding to the CO2capture strategies. Besides, the CO2utilization by the membrane process has also been highlighted.

Hollow fibre-based after-treatments impregnated with iron and chromium-based oxides (non-PGM) have been tested for residual methane catalytic oxidation under extreme conditions (sulfur concentration 100-times larger than in real conditions), real timeframes (1000 h) and real operating cycles (thermal shocks). The results from this study have proven, for the first time reported in the literature, that hollow fibre reactors can be scaled up and that non-PGM impregnated hollow fibre after-treatments are the ideal candidate for the development of commercial residual methane after-treatments.

Alpine wetlands play a sensitive function in global carbon cycle during the ongoing climate warming, yet the temporal patterns of carbon dynamics from in situ ground‐based long‐term observations remain unclear. Here, we analyzed the continuous net ecosystem CO2exchange (NEE) measured with the eddy covariance technique over an alpine peatland on the northeastern Qinghai‐Tibetan Plateau from 2007 to 2016. The wetland acted as a net CO2source with a positive NEE (120.4 ± 34.8 gC m−2year−1, Mean ± SD), with the mean annual gross primary productivity (GPP) of 500.3 ± 59.4 gC m−2year−1and annual ecosystem respiration (RES) of 620.7 ± 74.2 gC m−2year−1. At the seasonal scale, the classification and regression trees (CART) analysis showed that aggregated growing season degree days (GDDs) were the predominant determinant on variations in monthly NEE and monthly GPP. Variations in monthly RES were determined by soil temperature (Ts). Furthermore, nongrowing season Ts had a significant positive correlation with the following year annual GPP (p< 0.05). Nongrowing season RES only accounted for about 25% of annual RES but had significant correlation with annual RES and annual NEE (p< 0.05). The further partial correlation analysis showed that nongrowing season air temperature (Ta, p= 0.05), rather than precipitation (PPT, p= 0.25) was a predominant determinant on variations in annual NEE. Our results highlighted the importance in carbon dynamics of climate fluctuations and CO2emission from the nongrowing season in alpine wetlands. We speculated that the vast peadlands would positively feedback to climate change on the Tibetan plateau where the nongrowing season warming was significant. CO2fluxes in alpine wetland during the nongrowing season were crucial for annual carbon balance of alpine wetlandThe hydrothermal conditions especially during the nongrowing season played crucial role in determining interannual CO2fluxesGlobal warming will exacerbate carbon loss in the alpine wetlands of the Qinghai‐Tibetan Plateau