钢渣中钙含量较高,利用钢渣替代天然矿石作为钙源进行碳酸化反应固存CO_(2)是一种前景广阔的固废利用与碳减排方法。采用间接湿法碳酸化,不仅能显著提高固碳效率,还可实现制备高纯度、高附加值的碳酸钙产品。以AOD不锈钢渣(AOD渣)为材料...钢渣中钙含量较高,利用钢渣替代天然矿石作为钙源进行碳酸化反应固存CO_(2)是一种前景广阔的固废利用与碳减排方法。采用间接湿法碳酸化,不仅能显著提高固碳效率,还可实现制备高纯度、高附加值的碳酸钙产品。以AOD不锈钢渣(AOD渣)为材料,首先对其进行化学分析和矿相分析,确定其具有较高的固碳潜力;然后基于间接湿法加速碳酸化过程,探究AOD渣中钙的高效浸出规律,采用正交试验和单因素试验探究浸出温度、盐酸物质的量浓度、液固比和搅拌转速对钙浸出效率的影响;最后进行碳酸化反应并利用X射线衍射仪(XRD)、扫描电子显微镜(SEM-EDS)和热重分析仪(TG-DTG)研究钙离子转化率、碳酸钙纯度和微观形貌。试验结果表明,盐酸物质的量浓度和液固比是影响钢渣中钙浸出的主要因素;随着浸出反应进行,硅基团溶解生成的硅酸胶体会阻碍AOD渣内部元素进一步溶出;升温和提高酸浓度可有效消除硅酸胶体的影响,促进钙溶出。以1.5 mol/L盐酸为浸出剂,在85℃、液固比为50 m L/g、搅拌速度为600 r/min的浸出条件下,AOD渣中钙的浸出率可达90.51%,通过热重试验分析,经间接碳酸化后制备的CaCO_(3)产物纯度为96.04%,钙的转化率达到83.96%。研究结果可为利用钢渣钙碳酸化固碳并协同制备高附加值CaCO_(3)产物的冶金固废高效资源化利用提供试验和理论基础。展开更多
The role of carbodiimide as dehydrant in the chemo‐,regio‐and stereoselective Pd(Ⅱ/0)‐catalyzed hydrocarboxylation of various alkynes with HCOOH releasing CO in situ is reported for the first time to obtainα,β‐...The role of carbodiimide as dehydrant in the chemo‐,regio‐and stereoselective Pd(Ⅱ/0)‐catalyzed hydrocarboxylation of various alkynes with HCOOH releasing CO in situ is reported for the first time to obtainα,β‐unsaturated carboxylic acids.Both symmetrical and unsymmetrical monoalkynes show good reactivity.Importantly,2,2’‐(1,4‐phenylene)diacrylic acid can also be synthesized in high yield through the dihydrocarboxylation of 1,4‐diethynylbenzene.Besides,an excellent result in gram scale experiment and TON up to 900 can be obtained,displaying the efficiency of this protocol.Notably,regulating the types and concentrations of dehydrant can control the CO generation,avoiding directly operating toxic CO and circumventing sensitivity issue to the CO amount.On the basis of the attractive features of formic acid including easy preparation through CO_(2) hydrogenation and efficient liberation of CO,this protocol using formic acid as bridging reagent between CO_(2) and CO can be perceived as an indirect utilization of CO_(2),offering an alternative method for preparing acrylic acid analogues.展开更多
文摘钢渣中钙含量较高,利用钢渣替代天然矿石作为钙源进行碳酸化反应固存CO_(2)是一种前景广阔的固废利用与碳减排方法。采用间接湿法碳酸化,不仅能显著提高固碳效率,还可实现制备高纯度、高附加值的碳酸钙产品。以AOD不锈钢渣(AOD渣)为材料,首先对其进行化学分析和矿相分析,确定其具有较高的固碳潜力;然后基于间接湿法加速碳酸化过程,探究AOD渣中钙的高效浸出规律,采用正交试验和单因素试验探究浸出温度、盐酸物质的量浓度、液固比和搅拌转速对钙浸出效率的影响;最后进行碳酸化反应并利用X射线衍射仪(XRD)、扫描电子显微镜(SEM-EDS)和热重分析仪(TG-DTG)研究钙离子转化率、碳酸钙纯度和微观形貌。试验结果表明,盐酸物质的量浓度和液固比是影响钢渣中钙浸出的主要因素;随着浸出反应进行,硅基团溶解生成的硅酸胶体会阻碍AOD渣内部元素进一步溶出;升温和提高酸浓度可有效消除硅酸胶体的影响,促进钙溶出。以1.5 mol/L盐酸为浸出剂,在85℃、液固比为50 m L/g、搅拌速度为600 r/min的浸出条件下,AOD渣中钙的浸出率可达90.51%,通过热重试验分析,经间接碳酸化后制备的CaCO_(3)产物纯度为96.04%,钙的转化率达到83.96%。研究结果可为利用钢渣钙碳酸化固碳并协同制备高附加值CaCO_(3)产物的冶金固废高效资源化利用提供试验和理论基础。
文摘The role of carbodiimide as dehydrant in the chemo‐,regio‐and stereoselective Pd(Ⅱ/0)‐catalyzed hydrocarboxylation of various alkynes with HCOOH releasing CO in situ is reported for the first time to obtainα,β‐unsaturated carboxylic acids.Both symmetrical and unsymmetrical monoalkynes show good reactivity.Importantly,2,2’‐(1,4‐phenylene)diacrylic acid can also be synthesized in high yield through the dihydrocarboxylation of 1,4‐diethynylbenzene.Besides,an excellent result in gram scale experiment and TON up to 900 can be obtained,displaying the efficiency of this protocol.Notably,regulating the types and concentrations of dehydrant can control the CO generation,avoiding directly operating toxic CO and circumventing sensitivity issue to the CO amount.On the basis of the attractive features of formic acid including easy preparation through CO_(2) hydrogenation and efficient liberation of CO,this protocol using formic acid as bridging reagent between CO_(2) and CO can be perceived as an indirect utilization of CO_(2),offering an alternative method for preparing acrylic acid analogues.
