Acid-activated and WO_x-loaded montmorillonite catalysts and their catalytic behaviors in glycerol dehydration

The use of H2SO4‐,HCl‐,H3PO4‐,and CH3COOH‐activated montmorillonite(Mt)and WOx/H3PO4‐activated Mt as catalysts for the gas‐phase dehydration of glycerol was investigated.The WOx/H3PO4‐activated Mt catalysts were prepared by an impregnation method using H3PO4‐activated Mt(Mt‐P)as the support.The catalysts were characterized using powder X‐ray diffraction,Fourier‐transform infrared spectroscopy,N2adsorption‐desorption,diffuse reflectance ultraviolet‐visible spectroscopy,temperature‐programmed desorption of NH3,and thermogravimetric analysis.The acid activation of Mt and WOx loaded on Mt‐P affected the strength and number of acid sites arising from H+exchange,the leaching of octahedral Al3+cations from Mt octahedral sheets,and the types of WOx(2.7≤x≤3)species(i.e.,isolated WO4/WO6‐containing clusters,two‐dimensional[WO6]polytungstates,or three‐dimensional WO3crystals).The strong acid sites were weakened,and the weak and medium acid sites were strengthened when the W loading on Mt‐P was12wt%(12%W/Mt‐P).The12%W/Mt‐P catalyst showed the highest catalytic activity.It gave a glycerol conversion of89.6%and an acrolein selectivity of81.8%at320°C.Coke deposition on the surface of the catalyst led to deactivation.

Poplar Plantation as an Agroforestry Approach:Economic Benefits and Its Role in Carbon Sequestration in North India

Poplar has gained popularity among farmers of Punjab,Haryana,Western Uttar Pradesh,and the foothills of Uttarakhand and Himachal Pradesh due to their fast growth rate and suitability for industrial uses such as pulp and timber production.Integrating poplar trees into agroforestry systems optimizes land resources and economic gains,as successful techniques have been developed to coordinate crop timing and arrangements effectively.Integrating poplar trees with agricultural crops provides additional income streams for farmers and contributes to soil conservation,biodiversity enhancement,and other environmental benefits.Farmers in these regions typically employ effective spacing of 5 m×4 m for block plantation and 1 m×3 m for row plantation.In the present study,a systematic literature review encompassing 137 English-language journal articles was conducted to assess the economic benefits of Poplar using discounted cash flow(DCF)analysis,considering short-rotation poplar(SRC)and very short-rotation poplar(vSRC)plantations alongside annual crops.The findings revealed that increasing canopy density led to a decline in crop yields by 37%,70%,and 99% at canopy densities of 30%,60%,and 90%,respectively,from early spring to harvest.Cost-benefit analysis in Saharanpur district,India,indicated average annual net returns of USD 346.36 for Poplar-based agrisilviculture,while monoculture yielded USD 140.73 per annum.Furthermore,economic analysis in Yamunanagar and Haridwar districts showed benefit-cost ratios ranging from 2.35 to 3.7.Additionally,Poplar block and boundary plantations were found to sequester significantly more carbon in long-lived biomass,serving as substitutes for fossil fuels(5.45 and 1.84 t ha-1 yr-1)in poplar-based systems with block and boundary plantations.The study suggested expanding spacing between tree rows may mitigate resource competition between plantations and crops.The study inferred that Poplar-based agroforestry may play a crucial role in climate mitigation programs by effectively sequestering atmospheric carbon and offering fuel,fodder,timber,and wood products,thereby alleviating pressure on existing natural forests.

儿童美术教育琐谈175

■幼儿画画儿就像孩子肚子饿了想吃、渴了想喝水一样简单。画画是解决精神需要,想吃是解决生理需求,这些都与知识技巧无关。■“孙子兵法”里有这么多计谋,其实归根结底就一句话——“知己知彼”。幼儿教育也一样,知道自己,懂得儿童,教育就成功了。