WO3/Al2O3-TiO2催化劑的制備及其在甘油氣相脫水制備丙烯醛中的應用

劉 濤, 王奐祎, 賀站鋒, 王 丹, 蔣 毅

(1. 中國科學院 成都有機化學研究所，四川 成都 610041； 2. 中國科學院大學，北京 100049)

近年來，生物柴油在全球的迅猛發展[1]致使副產物甘油的大量過剩，如何有效利用過剩的甘油成為一個重要的研究課題。比較有效的解決方式是將甘油通過化學法，如選擇性氧化、脫水、氫解、鹵化、酯化和醚化、蒸汽重整等途徑[2,3]轉化成附加值更高的化工產品。在這些轉化途徑中，甘油脫水制備丙烯醛[4]具有較大的發展潛力。

目前，用于甘油脫水制備丙烯醛的固體酸催化劑主要有四大類：氧化物[5～8]、雜多酸[9～11]、分子篩[12～14]和磷酸鹽[15～17]。其中含有WO3的催化劑具有較大的應用潛力。Arda Ulgen等報道WO3/ZrO2[5]或WO3/TiO2[8]催化甘油脫水制備丙烯醛，收率均在70%以上；Lauriol-Garbey P等[7]用SiO2修飾WO3/ZrO2為催化劑，反應150 h，轉化率達80%，丙烯醛選擇性>70%；Kraleva E等[18]報道W-SBA-15催化劑在280 ℃以下反應，轉化率達90%，丙烯醛選擇性>70%；Suprun W等[17]使用過渡金屬修飾鋁磷酸鹽為催化劑，其對丙烯醛的選擇性順序為：W>Mo>Cu>V～Fe>Cr>Mn>Ce。以上催化劑，雖然在甘油脫水制備丙烯醛的反應中，具有較佳的催化活性，但還難以實現商業化應用，新催化劑的開發仍是甘油脫水研究的熱點。工業Al2O3(含5 wt%TiO2)是一種廣泛使用的載體，而WO3/Al2O3-TiO2催化劑應用于甘油脫水高選擇性制備丙烯醛的相關研究還未見文獻報道。

Scheme1

1 實驗部分

1．1 儀器與試劑

NOVA 2200e型氮吸附儀；Rigaku D/max-2500/PC型X-射線衍射儀(XRD)；SC-200型和SC3000-B型氣相色譜儀[HP-INNOWAX毛細管柱(30 m×0.32 mm×0.25 μm)；載氣：高純N2；FID檢測器；1,2-丙二醇為內標]；STA449C型熱重分析儀(TGA)；自行組裝的TCD-GC裝置(內徑9 mm,長度35.0 cm)。

鎢酸銨(H40N10O41W12·xH2O),分析純，國藥集團化學試劑有限公司；30%過氧化氫，分析純，廣東光華化學廠有限公司；工業Al2O3(含5 wt%TiO2)，江蘇三劑實業有限公司，使用前于750 ℃焙燒2 h，研磨至40 目～60 目后備用。

在反應瓶中加入鎢酸銨2.94 g(0.97 mmol)和水10 mL，攪拌使其溶解；加入Al2O3載體10 g，攪拌均勻，于室溫浸漬24 h；于110 ℃干燥10 h制得Cat20[w(WO3)=20%]。

改變鎢酸銨用量，用類似方法制得Catw(表1)。

表 1 制備的實驗條件Table 1 Conditions of preparing

*w(WO3)=m(WO3)/[m(WO3)+m(Al2O3-TiO2)]×100%; T：焙燒溫度

1．3 甘油脫水制備丙烯醛反應

2 結果與討論

2.1 表征

2θ/(°)圖的XRD譜圖

Temperature/℃圖2 Cat20的TGA曲線Figure 2 TGA curvesl of Cat20

2.2 載體與催化劑的織構性質

表 2 載體和催化劑的織構性質Table 2 Textural properties of the support and catalysts

w/%圖3 w對脫水反應的影響*Figure 3 Effect of w on dehydration of glycerol over

Calcination temperature/℃圖4 焙燒溫度對脫水反應的影響Figure 4 Effect of calcination temperature on dehydration of glycerol over

Reaction temperature/℃圖5 反應溫度對脫水反應的影響Figure 5 Effect of reaction temperature on dehydration of glycerol over

(1)w

(2)焙燒溫度

2.4 反應溫度對反應的影響

2.5 催化劑的NH3-TPD

Temperature/℃圖的NH3-TPDFigure 6 NH3-TPD prfiles of

w/%圖總酸量與w(a)或焙燒溫度(b)的關系Figure 7 Effect of w(a) or calcination temperature(b) on the total amount of acid of

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