论文部分内容阅读
自第一次工业革命以来,传统的化石能源(煤炭,石油等)一直是能源消费的主体.但是,随着社会的进步和技术的发展,能耗不断增加.但是化石能源不仅储量有限,而且还会引起严重的环境问题(环境污染和温室效应).因此,清洁和可持续能源的研究与开发尤为重要,氢能是研究的重点之一.由于氢具有高能量密度、清洁和可持续性的特点,因而成为了最有前景的能源载体.然而,氢气的储存和运输困难严重限制了其在质子交换膜燃料电池中的实际应用.作为液态氢存储材料之一,甲酸在催化剂存在下于室温下即可分解.另外,甲酸分解制氢的反应中不会释放有毒有害气体,对环境友好.用于甲酸分解(FAD)的高效催化剂是制氢的关键材料.本文制备了由薄层氮化碳促进的高性能钯(Pd)基催化剂,用于甲酸分解.首先,通过一步法直接煅烧三聚硫氰酸,以获得氮化碳(C3N4-S),然后制备以C3N4-S为载体的Pd基FAD催化剂(Pd/C3N4-S).在三聚硫氰酸的热解过程中,—SH基团的溢出具有剥离作用,因此形成的C3N4为破碎的薄层,具有较大的比表面积和孔体积.由于改善的比表面积和孔体积以及大量的缺陷附着位点,C3N4-S载体可以有效地分散Pd纳米颗粒.此外,由于载体和金属之间的电子效应,该载体可以有效地调节催化剂表面上的Pd2+含量.因此,Pd/C3N4-S表现优异的FAD性能.在30℃下,该催化剂可将甲酸有效分解为CO2和H2,转换频率(TOF值)和质量比活性分别达到了2083 h-1和19.52 mol·g-1·h-1.并且气相色谱测试结果表明,气体产物中不含CO,表明Pd/C3N4-S催化剂具有优异的选择性.另外,Pd/C3N4-S催化剂也具有良好的稳定性.经过4次循环测试,催化性能仅下降了不到10％.该研究为研究高性价比、制备方法简单的甲酸制氢催化剂提供了一定的指导作用.“,”Since the First Industrial Revolution,traditional fossil energy(coal,petroleum,etc.)has been the most important energy source.However,with social progress and technological development,energy consumption continues to increase.But fossil energy not only has limited reserves,it also causes serious problems(environmental pollution,the greenhouse effect).Therefore,the research and development of clean and sustainable energy are particularly important.One research focus is hydrogen energy.Hydrogen is a promising energy carrier due to its high energy density,clean-burning characteristics,and sustainability.However,the challenges of hydrogen storage and transportation seriously limit its practical application in proton exchange membrane fuel cells.A potential solution is hydrogen storage in the form of a more stable precursor.One such precursor,formic acid,decomposes easily at room temperature in the presence of a catalyst without also producing toxic gases.Effective catalysts for formic acid decomposition(FAD)are key to hydrogen production by this method.In this study,a high-performance palladium(Pd)-based catalyst boosted by thin-layered carbon nitride was prepared for formic acid decomposition.First,trimeric thiocyanate was calcined by a one-step method to obtain carbon nitride(C3N4-S)directly,followed by fabrication of a Pd-based FAD catalyst with C3N4-S as support(Pd/C3N4-S).During the pyrolysis of thiocyanuric acid,the overflow of-SH in the precursor had a peeling effect,so that the C3N4 formed as a thin,broken layer with a large specific surface area and pore volume.Because of the improved specific surface area and pore volume and the resulting large number of defect attachment sites,the C3N4-S support effectively dispersed Pd nanoparticles.Furthermore,owing to the electron effect between the support and the metal,the Pd2+content on the catalyst surface could be adjusted effectively.Pd/C3N4-S showed excellent FAD performance.This catalyst decomposed formic acid into CO2 and H2 effectively at 30℃.The turnover frequency and mass activity were as high as 2083 h-1 and 19.52 mol·g-1h-1,respectively.Testing of the gas product by gas chromatography showed that it did not contain CO,indicating that the Pd/C3N4-S catalyst had excellent selectivity.The catalyst also had good stability:its performance decreased by less than 10％after four testing cycles.This study provides a guiding example of development of a formic acid hydrogen production catalyst with high cost performance and a simple preparation method.