The limited CO_(2)content in aqueous solution and low adsorption amount of CO_(2)on catalyst surface lead to poor photocatalytic CO_(2)reduction activity and selectivity.Herein,the design and fabrication of a novel ph...The limited CO_(2)content in aqueous solution and low adsorption amount of CO_(2)on catalyst surface lead to poor photocatalytic CO_(2)reduction activity and selectivity.Herein,the design and fabrication of a novel photocatalytic architecture is reported,accomplished via chemical vapor deposition of polymeric carbon nitride on carbon paper.The as-obtained samples with a hydrophobic surface exhibit excellent CO_(2)transport and adsorption ability,as well as the building of triphase air-liquid-solid(CO_(2)-H_(2)O-catalyst)joint interfaces,eventually resulting in the inhibition of H2 evolution and great promotion of CO_(2)reduction with a selectivity of 78.6%.The addition of phosphate to reaction environment makes further improvement of CO_(2)photoreduction into carbon fuels with a selectivity of 93.8%and an apparent quantum yield of 0.4%.This work provides new insight for constructing efficient photocatalytic architecture of CO_(2)photoreduction in aqueous solution and demonstrates that phosphate could play a key role in this process.展开更多
常规的碳捕集与封存技术和碳捕集、利用与封存技术多针对固定源排放CO_(2),直接空气捕集CO_(2)(Direct Air Capture,DAC)技术作为一种新兴的负碳排放技术可对分布源排放的CO_(2)进行捕集,进一步降低全球大气CO_(2)体积分数。介绍了DAC...常规的碳捕集与封存技术和碳捕集、利用与封存技术多针对固定源排放CO_(2),直接空气捕集CO_(2)(Direct Air Capture,DAC)技术作为一种新兴的负碳排放技术可对分布源排放的CO_(2)进行捕集,进一步降低全球大气CO_(2)体积分数。介绍了DAC典型液体吸收工艺、固体吸附工艺的发展过程及相关示范项目建设情况,分析了新兴DAC工艺的技术特点,探讨了现有DAC工艺关键装置方案和未来发展趋势。DAC液体吸收工艺具有吸收剂原料成本较低、选择性较高的特点,可实现大规模连续化捕集,但再生过程中能耗较高。DAC固体吸附工艺具有模块化、投资成本较低的特点,且再生过程能耗相对较低,但需要定期对吸附材料更换和吸附设备维护,适用于较小规模的DAC应用场景。对2种典型DAC工艺吸收/吸附材料进行了概述。DAC电振荡吸附工艺中CO_(2)在固体电极中发生化学反应被捕集,并通过外加电场改变固体电极极性实现CO_(2)脱附,该工艺具有比基于热量或压力的分离过程更高的效率。空气中CO_(2)选择透过DAC分离膜从而实现了高效碳捕集。DAC变湿吸附工艺通过湿度的改变实现CO_(2)的吸脱附,突破了常规变温/变压吸附的高能耗限制等问题。DAC生物吸收工艺通过藻类生物的光合作用将CO_(2)吸收固定。基于双功能催化剂的DAC工艺可以在一个综合过程中实现CO_(2)的捕集与催化,节省了CO_(2)捕集后的运输与存储成本。DAC液体吸收工艺的关键装置为空气接触器、颗粒反应器、煅烧炉和熟化器,其中空气接触器开发的核心在于提高气液接触效率,减少喷淋过程中的水分损失和减轻设备腐蚀,颗粒反应器和熟化器开发的关键在于提高固液两相物料的接触效率以及反应后的固液分离效率。DAC固体吸附工艺由引风模块、吸附/再生模块、供能再生模块和CO_(2)压缩模块组成的模块化装置组成,其中优化吸附模块的核心在于提高气固传质速率、调谐CO_(2)捕集效率、降低压降;并基于不同应用场景工艺需求选择合适的再生系统或利用清洁能源,优化DAC工艺过程和开发高性能的DAC核心装置至关重要。展开更多
为了探究典型金属粉末对燃料空气炸药(fuel air explosive,FAE)冲击波效应和热毁伤性能的影响,采用20 L球形液体爆炸测试系统并结合比色测温方法,深入研究了不同金属粉种类和含量下环氧丙烷(epoxypropane,PO)的燃爆特性、火焰结构及温...为了探究典型金属粉末对燃料空气炸药(fuel air explosive,FAE)冲击波效应和热毁伤性能的影响,采用20 L球形液体爆炸测试系统并结合比色测温方法,深入研究了不同金属粉种类和含量下环氧丙烷(epoxypropane,PO)的燃爆特性、火焰结构及温度分布特征。实验结果表明:纯环氧丙烷的最佳质量浓度为780 g/m^(3),最大爆燃超压Δp_(max)=0.799 MPa,最大压力上升速率(dp/dt)_(max)=52.438 MPa/s。添加Al粉、Ti粉和Mg粉的环氧丙烷最大燃爆超压、最大压力上升速率和最大火焰平均温度均随着金属粉末质量比(I)的增加而增大,而最大压力上升时间的变化趋势则与之相反;最大燃爆超压和最大火焰平均温度的变化规律一致,从大到小依次为:Al/PO、Mg/PO、Ti/PO,且当金属粉的质量比I=40%时,3种固-液混合燃料的?pmax值相较于纯环氧丙烷分别增加了12.00%、8.41%和11.54%;此外,最大压力上升速率和燃烧速率的变化规律一致,从大到小依次为:Mg/PO、Al/PO、Ti/PO,且当金属粉的质量比I=40%时,3种固-液混合燃料的(dp/dt)max值相较于纯环氧丙烷分别增加了41.91%、39.60%和45.29%。研究结果表明,不同高能金属粉末在改善环氧丙烷燃爆性能方面各有优势,在FAE的配方设计时,应根据毁伤性能指标合理选择金属粉末作为含能添加剂。展开更多
文摘The limited CO_(2)content in aqueous solution and low adsorption amount of CO_(2)on catalyst surface lead to poor photocatalytic CO_(2)reduction activity and selectivity.Herein,the design and fabrication of a novel photocatalytic architecture is reported,accomplished via chemical vapor deposition of polymeric carbon nitride on carbon paper.The as-obtained samples with a hydrophobic surface exhibit excellent CO_(2)transport and adsorption ability,as well as the building of triphase air-liquid-solid(CO_(2)-H_(2)O-catalyst)joint interfaces,eventually resulting in the inhibition of H2 evolution and great promotion of CO_(2)reduction with a selectivity of 78.6%.The addition of phosphate to reaction environment makes further improvement of CO_(2)photoreduction into carbon fuels with a selectivity of 93.8%and an apparent quantum yield of 0.4%.This work provides new insight for constructing efficient photocatalytic architecture of CO_(2)photoreduction in aqueous solution and demonstrates that phosphate could play a key role in this process.
文摘常规的碳捕集与封存技术和碳捕集、利用与封存技术多针对固定源排放CO_(2),直接空气捕集CO_(2)(Direct Air Capture,DAC)技术作为一种新兴的负碳排放技术可对分布源排放的CO_(2)进行捕集,进一步降低全球大气CO_(2)体积分数。介绍了DAC典型液体吸收工艺、固体吸附工艺的发展过程及相关示范项目建设情况,分析了新兴DAC工艺的技术特点,探讨了现有DAC工艺关键装置方案和未来发展趋势。DAC液体吸收工艺具有吸收剂原料成本较低、选择性较高的特点,可实现大规模连续化捕集,但再生过程中能耗较高。DAC固体吸附工艺具有模块化、投资成本较低的特点,且再生过程能耗相对较低,但需要定期对吸附材料更换和吸附设备维护,适用于较小规模的DAC应用场景。对2种典型DAC工艺吸收/吸附材料进行了概述。DAC电振荡吸附工艺中CO_(2)在固体电极中发生化学反应被捕集,并通过外加电场改变固体电极极性实现CO_(2)脱附,该工艺具有比基于热量或压力的分离过程更高的效率。空气中CO_(2)选择透过DAC分离膜从而实现了高效碳捕集。DAC变湿吸附工艺通过湿度的改变实现CO_(2)的吸脱附,突破了常规变温/变压吸附的高能耗限制等问题。DAC生物吸收工艺通过藻类生物的光合作用将CO_(2)吸收固定。基于双功能催化剂的DAC工艺可以在一个综合过程中实现CO_(2)的捕集与催化,节省了CO_(2)捕集后的运输与存储成本。DAC液体吸收工艺的关键装置为空气接触器、颗粒反应器、煅烧炉和熟化器,其中空气接触器开发的核心在于提高气液接触效率,减少喷淋过程中的水分损失和减轻设备腐蚀,颗粒反应器和熟化器开发的关键在于提高固液两相物料的接触效率以及反应后的固液分离效率。DAC固体吸附工艺由引风模块、吸附/再生模块、供能再生模块和CO_(2)压缩模块组成的模块化装置组成,其中优化吸附模块的核心在于提高气固传质速率、调谐CO_(2)捕集效率、降低压降;并基于不同应用场景工艺需求选择合适的再生系统或利用清洁能源,优化DAC工艺过程和开发高性能的DAC核心装置至关重要。
