Xin Su,Guosheng Li,Chao Fan,Tingting Zhou,Jing Liu,Beibei Yan,Yang Zhang,Guanyi Chen,Jingang Yao
Herein, the SAPO-31 produced phenol-rich bio-oil from Arundo donax (AD) via catalytic fast pyrolysis (CFP) in a fixed bed. Effective variables including type of catalyst, temperature, weight hourly space velocity (WHSV) and N 2 flow rate (Nfr) were evaluated to enhance the CFP. The results showed that SAPO-31 demonstrated selectivity of 80.28 % towards naphtha-range compounds and 33.57 % towards phenolic compounds (PCs) within the naphtha range at 500 °C, Nfr of 300 mL min −1 and WHSV of 1 h −1 , contrasting sharply with those of control groups (50.82 % and 14.40 %, respectively), HZSM-5 (67.66 % and 5.51 %, respectively) and Hβ (61.10 % and 25.50 %, respectively). Moreover, SAPO-31 gave the highest bio-oil yielded (26.97 wt%) compared to that of the control group (22.45 wt%), Hβ (22.21 wt%) and HZSM-5 (21.42 wt%). These results indicate that the SAPO-31 self-synthesized exhibits promising capabilities in producing phenol-rich naphtha-range compounds via the CFP of AD.
Jun Wang,Qing Kuang,Xiaofang Su,Xiaowen Lu,Leipeng Leng,Mingyang Zhang,Chunmu Guo,Tong Li,Qian Xu,Shuhui Sun,J. Hugh Horton,Wei Wu,Zhijun Li
Supported single-atom catalysts have become one of the most exciting frontiers in heterogeneous catalysis. The physicochemical properties of these materials are highly interesting; however, the generation of stable single atoms on solid supports is still challenging. Herein, we report an efficient and operationally simple postsynthesis method, consisting of spatial confining, freeze-drying, and reducing steps, for the construction of singly dispersed palladium atoms on SAPO-31 (Pd1/SAPO-31) with promising application prospects in the semihydrogenation of alkynes. A typical Pd–N–C single-atom catalyst derived from the ZIF-8-supported palladium complex was prepared and compared to Pd1/SAPO-31. The Pd1/SAPO-31 catalyst showed outstanding performance in the semihydrogenation of both phenylacetylene (85% selectivity at 99% conversion, 40 min) and 1-chloro-4-ethynylbenzene (95% selectivity at 99% conversion, 60 min). In addition, this single-atom palladium catalyst was highly active in triethoxysilane oxidation. Most importantly, this catalyst retained its atomic dispersion and catalytic activity after high-temperature thermal treatment in Ar at 700 °C. This study demonstrates how zeolites can be used to confine atomically dispersed metal species and tune the activity and stability of these materials to meet the needs of practical applications.
Lu Xiaowen,Guo Chunmu,Zhang Mingyang,Leng Leipeng,Horton J. Hugh,Wu Wei,Li Zhijun
Chemoselective hydrodeoxygenation of vanillin is of great importance in converting biomass into high value-added chemicals. Herein, we describe a facile photochemical route to access palladium single atoms and clusters supported on silicoaluminophosphate-31 (SAPO-31) as a highly active, chemoselective, and reusable catalyst for hydrodeoxygenation of vanillin. Characterizations by aberration-corrected high-angle annular dark-field scanning transmission electron microscopy, extended X-ray absorption fine structure measurement, and CO-absorbed diffuse reflectance infrared Fourier transform spectroscopy reveal the atomically dispersed palladium single atoms and clusters are loosely bonded and randomly dispersed, without forming strong palladium-palladium metallic bonding, over the SAPO-31 support. This catalyst, with a full metal availability to the reactants, exhibits exceptional catalytic activity (TOF: 3,000 h −1 , Yield: > 99%) in the hydrodeoxygenation of vanillin toward 2-methoxy-4-methylphenol (MMP) under mild conditions (1 atm, 80 °C, 30 min), along with excellent stability, scalability (up to 100-fold), and wide substrate scope. The superior catalytic performance can be attributed to the synergistic effect of the positively charged palladium single atoms and fully exposed clusters, as well as the strong metal-support interactions. This work may offer a new avenue for the design and synthesis of fully exposed metal catalysts with targeted functionalities.
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