高级检索+

Cu掺杂多孔金属氧化物催化竹材的定向液化

Directional Liquefaction of Bamboo Catalyzed by Cu Doped Porous Metal Oxide

  • 摘要: 以类水滑石为前驱体,制备了Cu掺杂的多孔金属氧化物(PMO)催化剂,并采用ICP、BET和XPS等分析方法对催化剂进行了表征。ICP分析表明:催化剂负载的金属种类和含量与实验设计相符,表明类水滑石在形成及锻烧过程中金属离子损失较少;BET分析显示:Cu掺杂的PMO比未掺杂的PMO具有更大的比表面积,且比表面积随着Cu掺杂量的增加而降低;催化反应后PMO由绿色变为红色,XPS分析表明颜色变化伴随着Cu (Ⅱ)被还原为Cu (I)/Cu (0)的过程。在超临界甲醇体系中,考察了不同条件对PMO催化竹材液化率和液化产物组成的影响,结果表明:在Cu0.2Mg0.8Al-LDO用量为10%、反应温度为280℃、反应时间为8 h时,液化率达到了95.7%,液化产物中醇类和酮类的质量分数达到了55.7%,而且几乎没有酸类产生,表明竹材经过解聚/加氢后定向转为以小分子醇类和酮类为主的液体产物。随着Cu掺杂量和催化剂用量的增加,酮类、醇类以及烃类等氧含量较低的产物都有较大幅度提升,而酯类的量显著下降。甲醇的超临界温度(239℃)是反应产物组成与分布的关键临界点,醇类、酮类以及烃类产物的含量总体上随着反应时间的延长而增加。Cu掺杂的PMO催化剂是从甲醇中原位制氢实现竹材氢解和加氢的有效催化剂。

     

    Abstract: Cu doped porous metal oxide (PMO) catalysts were prepared using hydrotalcite-like compound as precursors. The synthesized catalysts were characterized by ICP, BET and XPS. The ICP analysis showed that metal loaded on the catalysis equated with the experiment design, which indicated that no obvious mass loss of metal ion during the formation and calcinations of hydrotalcite-like compound. BET analysis indicated a higher surface area in the doped PMO than the undoped. Appearance of PMO catalysts changed from green to red after the reaction. XPS studies showed that the color change was accompanied with the reduction of Cu (Ⅱ) to Cu(I)/Cu(0). The effects of reaction parameters on the liquefaction and products composition of bamboo were investigated in supercritical methanol medium. The results showed that under the conditions of 10% Cu0.2Mg0.8Al-LDO, reaction temperature of 280℃, and reaction time of 8 h, the liquefaction rate was 95.7%, the contents of alcohols and ketones in the liquefaction product were 55.7%, and almost no acid was found, indicating that the bamboo was converted to the liquid product mainly composed of small alcohols and ketones after depolymerization and hydrogenation. The amounts of products with low oxygen content such as ketones, alcohols and hydrocarbons increased with the increase of Cu doping levels and more catalysts dosage, while the amount of ester decreased significantly. The supercritical temperature of methanol was a key factor for the composition and distribution of the products. Generally, longer time resulted in higher contents of alcohols, ketones and hydrocarbons. These results supported that Cu doped PMO catalyst was an effective catalyst for both hydrogenolysis and hydrogenation of bamboo by in situ produced H2 from methanol.

     

/

返回文章
返回