磷灰石型催化剂的合成及其催化性能研究

采用水热法制备了羟基磷灰石(HAp),用离子交换法将Cl、Cu2+先后交换到磷灰石上制得氯磷灰石ClAp和Cu(Ⅱ)ClAp,用NaOH和水合肼将Cu(Ⅱ)ClAp还原为Cu(Ⅰ)ClAp,利用XRD、IR、XPS和原子吸收等方法对催化剂进行了表征.将制得的催化剂Cu(Ⅰ)ClAp首次应用于甲醇液相氧化羰基化合成碳酸二甲酯的反应中,考察了Cu(Ⅱ)ClAp制备温度,NaOH和水合肼用量对催化剂性能的影响.在反应中,由于Cl是通过固态离子交换法代替了HAp结构中的OH,Cu+取代了磷灰石晶格中的部分Ca2+,在反应的过程中Cl与Cu+不易脱落,减少了催化剂对设备的腐蚀性,且作为多相催化剂,易于回收利用.

Preparation of Apatite Catalysts and the Catalytic Activity for Oxidative Carbonylation of Methanol

Hydroxyapatite(Hap)was prepared by the hydrothermal method,ClAp and Cu(Ⅱ)ClAp were synthesized by the ion exchange method and then the Cu(Ⅱ)CIAp was deoxidized to the Cu(Ⅰ)ClAp with hydrazine hydrate (N_2H_4·H_2O)and sodium hydroxide (NaOH).The samples were characterized by XRD,IR,XPS and atomic absorption spectrometry.The catalysts Cu(Ⅰ)ClAp were used firstly in the reaction of synthesis of dimethyl carbonate (DMC) via liquid-phase oxidative carbonylation of methanol,the effect of prepared temperature for Cu(Ⅱ)ClAp,hydrazine hydrate (N_2H_4·H_2O)/sodium hydroxide (NaOH)/chlorapatitethe (CIAp) molar ratios were evaluated.The CL~- was introduced to Hap to substitute OH~-by solid-ion exchange method,Ca~(2+)of Hap was substituted partly by Cu~+,so the catalysts could decrease corrosiveness to vessels and could be reused effectively.