蒸气重整轻质生物油催化制氢研究进展

Research progress on catalytic hydrogen production based on steam reforming of light bio-oil

H_(2)作为一种高能量密度且环境友好型能源而备受关注,目前主要的制氢方法有化石燃料制氢、电解水制氢、生物质制氢等。生物质为碳中性资源,对实现我国“双碳”目标具有推动作用。生物质通过中温热解或水热解制得的生物油具有热值低、酸性强、黏度大等缺点,生物油中轻重组分须分别重整以生产高附加值的产品。生物油的轻质组分相对简单且成本低廉、转化途径经济可行,因此蒸气重整并催化制氢是很有前景的制氢方法。其中,催化剂的选择是影响轻质生物油制氢效率和稳定性最关键因素。综述了近年来基于蒸气重整的轻质生物油催化制氢的研究进展,重点介绍了传统蒸气重整、吸附增强的蒸气重整、自热蒸气重整、化学链蒸气重整和吸附增强的化学链蒸气重整等技术原理,归纳比较了催化剂、CO_(2)吸附剂对制氢性能的影响。传统蒸气重整技术中,相比贵金属催化剂高昂的制氢成本,Ni基催化剂因其低成本和较高制氢性能一直受到青睐,但仍需通过复合活性金属改性等方式改善其易烧结和积碳的缺陷。而吸附增强蒸气重整技术可通过CO_(2)原位吸附一定程度上提高制氢的产率和纯度。类水滑石化合物CO_(2)吸附剂碱性强、比表面积大,但需改性提高CO_(2)吸附温度以适应轻质生物油蒸气重整的温度。碱金属CO_(2)吸附剂稳定性强但成本较高。而CaO吸附剂成本低并在中高温下具有优良的CO_(2)吸附特性,成为最有应用前景的吸附剂之一。自热重整过程结合了蒸气重整与部分氧化制氢的优势,但需消耗O_(2)且易导致催化剂失活。吸附增强的化学链蒸气重整技术是载氧、载热和催化多功能颗粒的化学链路线耦合CO_(2)吸附,将化学链的自热优势以及吸附CO_(2)增强H_(2)产率的优点相结合,具有广泛的应用潜力。但其催化、吸附过程热质流率不匹配、吸附剂碳酸化速率影响催化作用规律等问题需进一步研究解决。

Hydrogen,as a high energy density and environment-friendly energy,has attracted much attention.At present,the main sources of hydrogen production include fossil fuels,water,biomass,etc.Biomass is a carbon neutral resource,which can promote the realization of China′s"Dual Carbon"goal.The bio-oil produced by biomass pyrolysis or hydrolysis has the disadvantages of low calorific value,strong acidity and high viscosity.The light and heavy components in bio-oil should be reformed separately to produce high value-added products.The components in light bio-oil are relatively simple,cheap and the conversion route is economical and feasible,the catalytical steam reforming of bio-oil is generally considered to be a promising hydrogen production way and the selection of catalyst is the most key factor affecting the efficiency and stability of hydrogen production.In this paper,the recent researches on hydrogen production from catalytic with steam reforming of light bio-oil were reviewed.The process principles of traditional steam reforming,adsorption enhanced steam reforming,autothermal steam reforming,chemical looping steam reforming and sorption-enhanced chemical looping steam reforming were emphatically introduced,and the effects of catalysts and CO_(2)adsorbents on hydrogen production performance were summarized and compared.Compared with expensive noble metal catalysts in the traditional steam reforming technology,the Ni-based catalyst has been widely recognized because of its low cost and high hydrogen production performance.However,the defects of easy sintering and carbon deposition still need to be improved by composite active metal modification.The adsorption-enhanced steam reforming technology can improve the yield and purity of hydrogen production through CO_(2)in-situ adsorption to a certain extent.The hydrotalcite like compound CO_(2)adsorbent has strong alkalinity and large specific surface area,but it needs to be modified to increase the CO_(2)adsorption temperature to meet the temperature needs of light bio oil steam reforming.Alkali metal CO_(2)adsorbent has strong stability but high cost.And CaO has become one of the most promising adsorbent due to its low cost and excellent CO_(2)adsorption characteristics at medium and high temperature.The autothermal reforming process combines the advantages of traditional and partial oxidation steam reforming to produce hydrogen,but it consumes O_(2) and easily leads to catalyst deactivation.The sorption-enhanced chemical looping steam reforming technology is the route of applying the oxygen carrying,heat carrying and catalytic multifunctional particles coupling CO_(2)adsorption,which combines the self-thermal advantages of chemical looping and enhanced adsorption advantages for high H_(2) purity,and has the potential of wide application.However,the mismatch of heat and mass flow rate in the catalytic and adsorption process,and the influence of carbonation process on catalysis need to be further studied.