Key Laboratory of Bio-Based Material Science and Technology (Ministry of Education), Northeast Forestry University, Harbin 150040, China.
Molecules. 2023 May 22;28(10):4245. doi: 10.3390/molecules28104245.
A niobium-doped HZSM-5 (H[Nb]ZSM-5) was prepared by a hydrothermal synthesis method. The morphology, phase structure, composition, pore structure, and acid content of the catalyst were characterized using a series of analysis techniques such as scanning electron microscope (SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption-desorption, and temperature programmed desorption measurements (NH-TPD). The H[Nb]ZSM-5 catalyst fully remained within the crystal framework and pore structure of HZSM-5. Meanwhile, introduction of niobium (V) endowed the catalyst with both Lewis acid and Bronsted acid sites. Catalytic fast pyrolysis (CFP) of alkali lignin was carried out through a pyrolysis and gas chromatography-mass spectrometry (Py-GC/MS) at 650 °C and atmospheric pressure. The results indicated that H[Nb]ZSM-5 can efficiently and selectively convert lignin into monoaromatic hydrocarbons (MAHs), compared to the control HZSM-5. Catalyzed by H[Nb]ZSM-5, the content of MAHs and aliphatic hydrocarbons reached 43.4% and 20.8%, respectively; while under the catalysis of HZSM-5, these values were 35.5% and 3.2%, respectively. H[Nb]ZSM-5 remarkably lowered the phenol content to approximately 2.8%, which is far lower than the content (24.9%) obtained under HZSM-5 catalysis.
采用水热合成法制备了一种掺铌 HZSM-5（H[Nb]ZSM-5）。采用扫描电子显微镜（SEM）、能谱（EDX）、X 射线衍射（XRD）、X 射线光电子能谱（XPS）、氮气吸附-脱附、程序升温脱附（NH-TPD）等一系列分析技术对催化剂的形貌、相结构、组成、孔结构和酸含量进行了表征。H[Nb]ZSM-5 催化剂完全保留了 HZSM-5 的晶体骨架和孔结构。同时，引入五价铌赋予了催化剂路易斯酸和布朗斯台德酸位。在 650°C 和常压下，通过热解和气相色谱-质谱联用（Py-GC/MS）对碱木质素进行了催化快速热解（CFP）。结果表明，与 HZSM-5 相比，H[Nb]ZSM-5 可以有效地将木质素选择性转化为单芳烃（MAHs）。在 H[Nb]ZSM-5 的催化作用下，MAHs 和脂肪族烃的含量分别达到 43.4%和 20.8%；而在 HZSM-5 的催化作用下，这两个值分别为 35.5%和 3.2%。H[Nb]ZSM-5 显著降低了苯酚的含量，约为 2.8%，远低于 HZSM-5 催化时的含量（24.9%）。
