Zn/Co-ZIF衍生多孔碳钯基催化剂的制备及在甲酸制氢中的应用

Preparation of Zn/Co-ZIF derived porous carbon supported Pd as catalyst and its application to formic acid dehydrogenation

通过浸渍还原法将Pd、Ag等锚定在经过HNO_(3)酸化和(NH_(4))_(2)HPO_(4)磷化处理得到的Zn/Co-ZIF衍生HPNC多孔碳上,制备出高活性的Ag_(1)Pd_(7)@HPNC催化剂。采用XRD、TEM、SEM和EDS等系列表征手段对Zn/CoZIF、多孔碳载体和制备的催化剂进行了表征分析和系统测试。结果表明,多孔碳中的Zn和大部分的Co物种可通过高温焙烧和酸化处理方式被有效去除,小尺寸的Pd和Ag纳米颗粒可高效负载于HPNC多孔碳载体的表面。通过探究不同载体及银钯不同的质量比对催化剂催化活性的影响,证明了Ag_(1)Pd_(7)@HPNC催化剂具有优异的甲酸催化性能。甲酸分解实验表明,经(NH_(4))_(2)HPO_(4)处理后的Pd@HPNC催化剂活性优于未处理的Pd@HNC催化剂活性。掺杂Ag会进一步提高Ag_(x)Pd_(y)@HPNC(x>0)双金属催化剂的催化活性,其中当m_(Ag)∶m_(Pd)=1∶7时,Ag_(1)Pd_(7)@HPNC催化甲酸分解活性最佳,在318 K条件下甲酸分解的转化频率(TOF)可达1025 h^(-1);并且该催化剂循环使用5次后TOF仍保持为920 h^(-1),表明其具有良好的循环稳定性。Ag_(1)Pd_(7)@HPNC在甲酸催化脱氢方面展示了较好的应用前景。

Highly active Ag_(1)Pd_(7)@HPNC catalyst were obtained through anchoring Ag and Pd on Zn/Co-ZIF derived nitrogen-doped porous carbon(HPNC),which was obtained by HNO_(3)immersion and(NH_(4))_(2)HPO_(4)phosphating.Zn/Co-ZIF,porous carbon supports and prepared catalysts were characterized and systematically analyzed by a series of characterization methods such as XRD,TEM,SEM and EDS,etc.The results showed that Zn and most of Co species in porous carbon could be effectively removed by high-temperature sintering and acidification treatment,and small-size Pd and Ag nanoparticles could be efficiently loaded on the surface of HPNC porous carbon carriers.By exploring the effects of different catalyst supports and different m_(Ag)∶m_(Pd)on the catalyst catalysts,it was demonstrated that the Ag_(1)Pd_(7)@HPNC catalysts had excellent formic acid catalytic activity.The formic acid dehydrogenation experiment showed that the catalytic activity of Pd@HPNC treated by(NH_(4))_2HPO_(4)was superior to that of untreated Pd@HNC catalyst,and the catalytic activity of Ag_(x)Pd_(y)@HPNC(x>0)prepared by doping Ag species had been further improved.When the mass ratio of m_(Ag)∶m_(Pd)=1∶7,the catalytic activity of Ag_(1)Pd_(7)@HPNC for formic acid decomposition was optimal with a turnover frequency(TOF)of 1025 h^(-1)for formic acid at318 K,and the catalyst was recycled for five times with the TOF value of 920 h^(-1),indicating its good recycling stability.Ag_(1)Pd_(7)@HPNC showed a good application prospect to formic acid dehydrogenation.