摘要
[目的] 5-羟甲基糠醛(HMF)是最重要的生物质基平台化学品之一,可以通过催化加氢途径制备许多高附加值化学品.本文为设计在更加温和的条件下达到高效催化HMF加氢的非贵金属催化剂进行了一系列研究.[方法]通过尿素共沉淀法制备了一种NiAl催化剂,考察了NiAl催化剂催化HMF加氢制备2,5-二羟甲基四氢呋喃(BHMTHF)的性能,并利用X射线衍射(XRD)、氢气程序升温还原(H_(2)-TPR)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、氨气程序升温脱附(NH_(3)-TPD)、X射线光电子能谱(XPS)等表征方法系统地研究了不同Ni/Al比、不同煅烧温度和还原温度对催化剂理化性质的影响.[结果] Ni和Al的投料原子比为3∶1,在350℃下煅烧、650℃下还原制备的催化剂Ni_(3)Al-350-650在100℃、氢气压力2.5 MPa的条件下反应1 h,HMF的转化率和BHMTHF产率分别高达99.5%和87.5%.过高的Ni/Al比制备的催化剂比表面积较小,导致暴露的活性位点较少从而降低了催化活性,通过煅烧温度可以调节NiAl催化剂的可还原性.[结论]本研究实现了在温和条件下HMF的高效催化加氢转化.该结果可为用于HMF定向转化的非贵金属催化剂的设计提供参考.
[Objective] 5-Hydroxymethylfurfural(HMF) is one of the most important biomass-based platform chemicals that serve as the raw material for the production of various high-value added chemicals through catalytic hydrogenation.This study investigates the effect of NiAl catalyst on the performance of HMF reduction to 2,5-bis(hydroxymethyl)tetrahydrofuran(BHMTHF).[Methods] In this study,NiAl catalysts were prepared using the urea coprecipitation method.The effects of different Ni/Al ratios,calcination temperature,and reduction temperature on the physicochemical properties of the catalysts were systematically studied using X-ray diffraction(XRD),H_(2) temperature-programmed reduction(H_(2)-TPR),scanning electron microscope(SEM),NH_(3 )temperature-programmed desorption(NH_3-TPD),X-ray photoelectron spectroscopy(XPS),transmission electron microscopy(TEM),and other characterization methods.The active hydrogenation reaction of the catalyst was carried out in a 25 mL reactor:0.25 g HMF,5 mL methanol and 0.125 g catalyst were placed into the reactor,followed by the addition of 2.5 MPa hydrogen.The reactor was then heated in a 100 ℃ oil bath.[Results] The phase structure of catalysts,prepared with different Ni/Al ratios and temperatures,and its impact on the hydrogenation activity of catalysts prepared from HMF to BHMTHF were thoroughly investigated.The results show that,with an increase in the Ni/Al ratio,the peaks corresponding to Al_(2)O_(3) become nearly undetectable,likely due to the weak intensity of the diffraction peaks.However,with the increase of the Ni/Al ratio,the specific surface area of the catalyst and the proportion of Al elements gradually decreases.This is accompanied by a reduction in intermediate acid sites and the total acid content,leading to speculation that the acidic sites are mainly provided by Al metal.In addition,with the increase of Ni/Al ratio,the proportion of Ni^(0) initially increases and then decreases,among which Ni_(3Al) had the best catalytic activity,and the peak area of Ni^(0) is relatively large,suggesting that Ni^(0) is the active component.The obvious NiO phase diffraction peaks and NiAl_(2)O_(4) phase diffraction peaks in the XRD pattern of Ni_(3)Al-650-650 indicate enhanced interaction between Ni species and Al_(2)O_(3) at higher calcination temperature of the catalyst.This interaction makes it more challenging to reduce NiO,thus increasing the difficulty of subsequent catalyst reduction and activation.With the increase in calcination temperature,the required reduction temperature of the sample gradually shifts to a high temperature,as observed in the comparison of the H_(2)-TPR spectra for oxides prepared at different calcination temperatures.This shift indicates that complete reduction to elemental Ni occurs at a higher temperature,consistent with the XRD characterization results.It is speculated that the reduced catalyst has the ability to activate hydrogen.During the second reduction,the active center activates part of hydrogen to form part of active hydrogen species,leading to a hydrogen consumption peak below 300 ℃.As the calcination temperature and reduction temperature increase,the crystal size of the catalyst continuously increases,the pore volume decreases,and the specific surface area decreases.The catalytic effect initially increases and then decreases.Among them,it is found that Ni_(3)Al-350-650,which has the highest BHMTHF yield,has the maximum medium-strength acid sites.[Conclusion] The catalytic performance of NiAl catalysts in the reduction of HMF to BHMTHF was investigated.A Ni/Al ratio that is too high will result in a small specific surface area,reducing the number of exposed active site,and thus,decreasing catalytic activity.The reducibility of NiAl catalyst precursors can be adjusted by the calcination temperature,which would in turn affect the catalytic activity of NiAl catalysts.This study achieves a 99.5% HMF conversion with a BHMTHF yield of 87.5%.This work holds significant guidance for the design of non-noble metal catalysts for HMF hydrogenation.
作者
曾安琪
闫贵花
孙勇
曾宪海
林鹿
唐兴
ZENG Anqi;YAN Guihua;SUN Yong;ZENG Xianhai;LIN Lu;TANG Xing(Fujian Engineering and Research Centre of Clean and High-Valued Technologies for Biomass,Xiamen Key Laboratory of Clean and High-Valued Utilization for Biomass,College of Energy,Xiamen University,Xiamen 361102,China)
出处
《厦门大学学报（自然科学版）》
CAS
CSCD
北大核心
2024年第1期82-93,共12页
Journal of Xiamen University：Natural Science
基金
国家自然科学基金(U22A20421,22078275)。
关键词
生物质
还原氢化
5-羟甲基糠醛
非贵金属
2
5-二羟甲基四氢呋喃
biomass
reduction hydrogenation
5-hydroxymethylfurfural
non-noble metal
2,5-bis(hydroxymethyl)tetrahydrofuran
