Ruoyan Yang

Recent advances in solid sorbents for CO2 capture and new development trends

Carbon dioxide (CO2) capture using solid sorbents has been recognized as a very promising technology that has attracted intense attention from both academic and industrial fields in the last decade. It is astonishing that around 2000 papers have been published from 2011 to 2014 alone, which is less than three years after our first review paper in this journal on solid CO2 sorbents was published. In this short period, much progress has been made and the major research focus has more or less changed. Therefore, we feel that it is necessary to give a timely update on solid CO2 capture materials, although we still have to keep some important literature results published in the past years so as to keep the good continuity. We believe this work will benefit researchers working in both academic and industrial areas. In this paper, we still organize the CO2 sorbents according to their working temperatures by classifying them as such: (1) low-temperature ( 400 °C). Since the sorption capacity, kinetics, recycling stability and cost are important parameters when evaluating a sorbent, these features will be carefully considered and discussed. In addition, due to the huge amounts of cost-effective CO2 sorbents demanded and the importance of waste resources, solid CO2 sorbents prepared from waste resources and their performance are reviewed. Finally, the techno-economic assessments of various CO2 sorbents and technologies in real applications are briefly discussed.

Synthesis of layered double hydroxides/graphene oxide nanocomposite as a novel high-temperature CO2 adsorbent

Abstract In this contribution, a novel high-temperature CO2 adsorbent consisting of Mg-Al layered double hydroxide (LDH) and graphene oxide (GO) nanosheets was prepared and evaluated. The nanocomposite-type adsorbent was synthesized based on the electrostatically driven self-assembly between positively charged Mg-Al LDH single sheet and negatively charged GO monolayer. The characteristics of this novel adsorbent were investigated using XRD, FE-SEM, HRTEM, FT-IR, BET and TGA. The results showed that both the CO2 adsorption capacity and the multicycle stability of LDH were increased with the addition of GO owing to the enhanced particle dispersion and stabilization. In particular, the absolute CO2 capture capacity of LDH was increased by more than twice by adding 6.54 wt% GO as support. GO appeared to be especially effective for supporting LDH sheets. Moreover, the CO2 capture capacity of the adsorbent could be further increased by doping with 15 wt% K2CO3. This work demonstrated a new approach for the preparation of LDH-based hybrid-type adsorbents for CO2 capture.

Layered double hydroxide (LDH) derived catalysts for simultaneous catalytic removal of soot and NOx

Nitrogen oxides (NO(x)) and soot which come from vehicle engine exhausts cause serious environmental pollution and human health problems. Recently, the catalytic purification technology, particularly the simultaneous catalytic removal of soot and NO(x), has received more and more attention. For this technology, the key is to develop highly efficient and robust catalysts. Due to the unique chemical and structural properties of layered double hydroxides (LDHs), LDH-derived catalysts have shown great potential, and much effort has been devoted to this type of catalyst. In this manuscript, we reviewed the latest progress in the LDH derived catalysts by classifying the LDH precursors according to the number of metals into binary, ternary, and quaternary, and discussed their advantages and disadvantages in detail. We hope that this review paper could provide a clearer picture of this topic and theoretical support for its better development.

Novel Na2Mo4O13/α-MoO3 hybrid material as highly efficient CWAO catalyst for dye degradation at ambient conditions

We report a novel hybrid material Na2Mo4O13/α-MoO3 as highly efficient catalytic wet air oxidation (CWAO) catalyst, which showed the highest ever activity at room temperature and atmosphere pressure for the degradation of cationic red GTL. SEM and TEM analyses indicated that this hybrid catalyst has bamboo-shaped nanofiber morphology. In view of practical applications, the influence of some key parameters including operation temperature, catalyst calcination temperature, and the volume of dye wastewater have been optimized. The mechanism for the superior catalytic performance was investigated. XRD, XPS, and ESR suggested the Na2Mo4O13/α-MoO3 hybrid catalyst possesses more O2− ions in the oxygen deficient regions than neat α-MoO3, promoting the formation of active ·OH radicals and resulting in a higher activity. Considering the facile preparation and its superior activity, this novel catalyst is promising for practical dye wastewater treatment.

Synthesis of Pt doped Mg–Al layered double oxide/graphene oxide hybrid as novel NOx storage–reduction catalyst

We report the synthesis of Pt doped Mg–Al layered double oxide/graphene oxide (Pt–LDO/GO) hybrid as novel NOx storage and reduction (NSR) catalyst. For the preparation of layered double hydroxide/GO hybrids, LDHs and graphite oxide were first exfoliated into single-layers, followed by self-assembly. LDO/GO hybrids were obtained by thermal treatment of LDH/GO. The obtained LDH/GO and LDO/GO hybrids were thoroughly characterized using XRD, SEM, TEM, FT-IR, and BET analyses. Then the NOx storage capacity of neat LDO and LDO(10)/GO hybrids were compared by isothermal NOx adsorption tests. The influence of adsorption temperature, gas flow, calcination temperature, and LDH dispersion concentration were systematically studied. The results demonstrated that the NOx storage capacity of neat LDO was significantly improved from 0.175 to 0.314 mmol g−1 by introducing only 7 wt% of GO, which could be attributed to the enhanced particle dispersion and stabilization. Moreover, the NOx storage capacity of the hybrid could be further increased close to 0.335 mmol g−1 catalyst by doping with 2 wt% Pt. The Pt–LDO(1)/GO also exhibited excellent lean-rich cycling performance, with an overall 71.7% of NOx removal. This work provided a new scheme for the preparation of highly dispersed LDH/GO hybrid type NSR catalyst.