Knoevenagel condensation catalysed by poly(vinyl chloride) supported tetraethylenepentamine (PVC-TEPA)

Poly（vinyl chloride） supported tetraethylenepentamine （PVC-TEPA） has been found to be an efficient catalyst for the Knoevenagel condensation. A wide range of aromatic aldehydes easily undergo condensations with ethyl cyanoacetate and malononitrile in the commercial 95% ethanol in refluxing using PVC-TEPA as catalyst to afford the desired products of good purity in moderate to excellent yields. A recycling study confirmed that the catalyst could be reused, the yield of the desired condensation product were not reduced. The merits of this protocol are environmentally benign, simple operation, convenient work-up and good yields. Furthermore, the catalyst can easily be recovered and reused at five times with comparable yields.

Optimization of CO_2 adsorption capacity and cyclical adsorption/desorption on tetraethylenepentamine-supported surface-modified hydrotalcite

The objective of this research was to investigate CO2adsorption capacity of tetraethylenepentamine-functionalized basic-modified calcined hydrotalcite（TEPA/b-c HT）sorbents at atmospheric pressure formed under varying TEPA loading levels,temperatures,sorbent weight to total gaseous flow rate（W/F）ratios and CO2concentrations in the influent gas.The TEPA/b-c HT sorbents were characterized by means of X-ray diffraction（XRD）,Fourier transform infrared spectrometry（FT–IR）,thermal gravimetric analysis（TGA）,Brunauer–Emmet–Teller（BET）analysis of nitrogen（N2）adsorption/desorption and carbon–hydrogen–nitrogen（CHN）elemental analysis.Moreover,a full 2~4factorial design with three central points at a 95%confidence interval was used to screen important factor（s）on the CO2adsorption capacity.It revealed that85.0%variation in the capacity came from the influence of four main factors and the15.0%one was from their interactions.A face-centered central composite design response surface method（FCCCD–RSM）was then employed to optimize the condition,the maximal capacity of 5.5–6.1 mmol/g was achieved when operating with a TEPA loading level of 39%–49%（W/W）,temperature of 76–90℃,W/F ratio of 1.7–2.60（g·sec）/cm^3and CO2concentration of 27%–41%（V/V）.The model fitted sufficiently the experimental data with an error range of±1.5%.From cyclical adsorption/desorption and selectivity at the optimal condition,the 40%TEPA/b-c HT still expressed its effective performance after eight cycles.

Additives enhancing supported amines performance in CO_(2)capture fromair

The utilization of supported amines as adsorbents in direct air capture(DAC)has been demonstrated to be a promising strategy for the reduction of CO_(2)emissions.To improve the performance of amine-based adsorbents,the incorporation of additives has been widely adopted.In the present study,we conduct a comprehensive comparison of seven additives on tetraethylenepentamine-impregnated mesoporous silica as a representative amine-based adsorbent.The results indicate thatminor molecularweight additiveswith hydroxyl groups show improved adsorption-desorption performance and increase oxidative stability.A proposed mechanism for these improvements is the combined physical and chemical promotion effects of hydroxyl groups.Through a comprehensive review of existing literature,it is found that the effects of additives on amine-based adsorbents are dependent on factors,such as additive type,pristine adsorbent properties,incorporation method,and testing conditions.Based on these findings,it is recommended that future DAC systems prioritize the use of hydroxyl-containing additives,whereas higher CO_(2)concentration and temperature capture may benefit from the incorporation of additives without hydroxyl groups.These conclusions are expected to contribute to the design of efficient adsorbents for CO_(2)capture.