Abstract:

W₂C/AC catalysts with different tungsten loadings were prepared by using the activated carbon (AC) as the carrier. These catalysts were mechanically mixed with the pine milled wood lignin (MWL) for Py-GC/MS (pyrolysis-gas chromatography/mass spectrometry) experiments to investigate the catalytic effects of tungsten loading and catalyst-to-MWL ratio on the distribution of pyrolytic products. Moreover, the actual yields of major pyrolytic products (aromatic hydrocarbons and phenolics) were quantitatively determined by the external standard method. The results indicated that the W₂C/AC catalyst could promote the pyrolytic depolymerization of MWL to generate momocyclic phenolic compounds. Furthermore, it could catalyze the decarbonylation, demethoxylation, dehydroxylation and hydrogenation reactions of phenolic compounds to form stable phenolics (without the carbonyl group, methoxyl group and unsaturated C=C bond) and aromatic hydrocarbons. Among the four W₂C/AC catalysts, the 10%-W₂C/AC possessed the best catalytic capability. The maximal yield of total pyrolytic products was obtained at the catalyst-to-MWL ratio of 5, and the total yields of aromatic hydrocarbons and phenolics at this condition reached 102.1 mg·g^-1 and 191.1 mg·g^-1, compared with the values of 21.2 mg·g^-1 and 151.0 mg·g^-1 in the absence of the catalyst.

Key words: W₂C/AC, catalysis, pyrolysis, MWL, hydrodeoxygenation, Py-GC/MS

摘要：

以活性炭（AC）为载体制备了不同钨负载量的W₂C/AC催化剂，将其和松木磨木木质素（MWL）机械混合后进行Py-GC/MS（快速热解-气相色谱/质谱联用）实验，考察了钨负载量、催化剂/MWL比例对产物分布的影响，并通过外标法对主要产物（芳烃类和酚类）的真实产率进行了定量分析。结果表明，W₂C/AC催化剂可有效促进木质素的热解解聚生成单酚类产物，并对酚类产物具有脱羰基、脱甲氧基、脱羟基以及加氢的效果，从而促进稳定的酚类产物（不含羰基、甲氧基和不饱和碳碳双键）和芳烃类产物的生成。在4种W₂C/AC催化剂中，10%-W₂C/AC的催化效果最佳，在催化剂/MWL比例为5时热解产物总产率达到最大值，此时芳烃类和酚类产物的总产率由无催化剂时的21.2 mg·g^-1和151.0 mg·g^-1增加至102.1 mg·g^-1和191.1 mg·g^-1。

关键词: W₂C/AC, 催化, 热解, 磨木木质素, 加氢脱氧, Py-GC/MS