Potentiometric titration method was used to judge whether the precipitated hydroxide is a complex hydroxide or a mixture when alkali solution was added to an aqueous solution containing two kinds of metal salts(Al 3+ ...Potentiometric titration method was used to judge whether the precipitated hydroxide is a complex hydroxide or a mixture when alkali solution was added to an aqueous solution containing two kinds of metal salts(Al 3+ ?Fe 3+ ?Ni 2+ ?Zn 2+ ?Cu 2+ ). Capability of complex formation between the metal hydroxides was investigated by comparing the pH of the plateau in the titration curves with that for the solution of one metal ion. Complex hydroxide was formed for all divalent ions and trivalent ions, and the sequence of the capability was Ni 2+ >Zn 2+ >Cu 2+ .展开更多
采用成核-晶化隔离法制备LiAl-CO_(3)-LDHs晶核,在LDHs晶核晶化的过程中引入葡萄糖分子作为碳源,构筑组成和结构可调的LDHs/C型杂化复合前体。通过高温处理,实现前体的结构拓扑转变及无定形碳组分的去除,得到高比表面积的LiAl复合金属...采用成核-晶化隔离法制备LiAl-CO_(3)-LDHs晶核,在LDHs晶核晶化的过程中引入葡萄糖分子作为碳源,构筑组成和结构可调的LDHs/C型杂化复合前体。通过高温处理,实现前体的结构拓扑转变及无定形碳组分的去除,得到高比表面积的LiAl复合金属氧化物型固体碱催化剂。采用XRD、FT-IR、BET、TEM、SEM、CO_(2)-TPD等表征手段对催化剂的组成、结构、织构性能、表面碱性进行了详细研究,并以苯甲醛和氰基乙酸乙酯间的Knoevenagel缩合反应为探针反应系统地研究了催化剂的碱催化性能。研究结果表明,LDHs/C杂化前体制备过程中葡萄糖与金属离子的摩尔比、水热晶化温度以及焙烧温度是影响催化剂活性的主要因素,晶化温度和焙烧温度的提升不利于碱性位的充分暴露。在150℃的水热晶化温度下,葡萄糖与Al 3+的摩尔比为3时的杂化复合前体经500℃焙烧得到的LiAl-MMO-150-3-500固体催化剂比表面积高达229 m 2·g^(-1),苯酚吸附测得催化剂的总碱量为855μmol·g^(-1),对苯甲醛的转化率高达88.21%。展开更多
文摘Potentiometric titration method was used to judge whether the precipitated hydroxide is a complex hydroxide or a mixture when alkali solution was added to an aqueous solution containing two kinds of metal salts(Al 3+ ?Fe 3+ ?Ni 2+ ?Zn 2+ ?Cu 2+ ). Capability of complex formation between the metal hydroxides was investigated by comparing the pH of the plateau in the titration curves with that for the solution of one metal ion. Complex hydroxide was formed for all divalent ions and trivalent ions, and the sequence of the capability was Ni 2+ >Zn 2+ >Cu 2+ .
文摘采用成核-晶化隔离法制备LiAl-CO_(3)-LDHs晶核,在LDHs晶核晶化的过程中引入葡萄糖分子作为碳源,构筑组成和结构可调的LDHs/C型杂化复合前体。通过高温处理,实现前体的结构拓扑转变及无定形碳组分的去除,得到高比表面积的LiAl复合金属氧化物型固体碱催化剂。采用XRD、FT-IR、BET、TEM、SEM、CO_(2)-TPD等表征手段对催化剂的组成、结构、织构性能、表面碱性进行了详细研究,并以苯甲醛和氰基乙酸乙酯间的Knoevenagel缩合反应为探针反应系统地研究了催化剂的碱催化性能。研究结果表明,LDHs/C杂化前体制备过程中葡萄糖与金属离子的摩尔比、水热晶化温度以及焙烧温度是影响催化剂活性的主要因素,晶化温度和焙烧温度的提升不利于碱性位的充分暴露。在150℃的水热晶化温度下,葡萄糖与Al 3+的摩尔比为3时的杂化复合前体经500℃焙烧得到的LiAl-MMO-150-3-500固体催化剂比表面积高达229 m 2·g^(-1),苯酚吸附测得催化剂的总碱量为855μmol·g^(-1),对苯甲醛的转化率高达88.21%。
