本研究以稻殼為原料，經過水洗、酸洗、熱解及碳燒等前處理方法，製成稻殼灰分，並以其為擔體，利用沈澱固著法製備成稻殼灰分擔體銅觸媒(簡稱為Cu/RHA觸媒)，同時輔以感應耦合電漿質譜儀(ICP-MS)、元素分析儀(EA)、感應耦合電漿原子放射光譜儀(ICP-AES)、氮吸附法、X射線繞射儀(XRD)、熱重分析儀(TGA)、程式升溫還原(TPR)、N2O分解吸附(dissociative adsorption of nitrous oxide)、掃描式電子顯微鏡(SEM)及穿透式電子顯微鏡(TEM)等各項儀器與分析技術，分別對擔體及觸媒進行特性分析，藉以評估稻殼灰分做為觸媒擔體的可行性。 在稻殼灰分的組成分析方面，從分析結果得知：二氧化矽的純度達99％，其晶態屬於非晶型的二氧化矽，氮吸附分析結果指出其BET比表面積約為113m2/g，為一非多孔性物質，孔洞形狀則為圓形，利用電子顯微鏡觀察其表面結構及粒子大小，可知其表面相當平滑、粒子大小約為100nm。 而在稻殼灰分擔體銅觸媒(Cu/RHA)方面，從分析結果得知：當恆溫沈澱時間超過12小時，有最大的銅負載量。沈澱固著乾燥後所形成的觸媒前趨物為一種類似孔雀石(chrysocolla-like)的層狀矽酸銅(copper hydrosilicate)結構，而矽酸銅熱分解溫度至少要673K。由氮吸附結果指出，不論是鍛燒後或還原後的Cu/RHA觸媒，其BET比表面積隨銅金屬載量增加而增加，而且高載量Cu/RHA觸媒的孔洞形狀呈狹縫型。從TPR圖譜可看出，Cu/RHA觸媒的還原溫度隨銅金屬載量增加而降低。從N2O分解吸附結果可知，Cu/RHA觸媒的分散度隨銅金屬載量增加而降低，但銅平均粒徑隨銅金屬載量增加而變大。從XRD圖譜也可看出銅粒徑有增加的趨勢。比較稻殼灰分與氧化矽膠的分析結果，稻殼灰分確實有異於氧化矽膠的擔體性質存在，不僅能負載較多的銅活性金屬，也可使負載於表面的銅金屬有較高的金屬表面積，而且分散性佳，未來應用於催化反應時，應有較佳的活性表現。 In this work, the rice husk ash (RHA) was used as a catalyst support. The RHA-supported copper catalysts (Cu/RHA) were prepared by the deposition-precipitation technique. The RHA and Cu/RHA catalysts were characterized by inductively coupled plasma-mass spectrometer (ICP- MS), element analysis (EA), inductively coupled plasma-atomic emission spectrometer (ICP-AES), nitrogen adsorption method, X-ray diffraction (XRD), thermogravimetric analyzer (TGA), temperature-programmed reduction (TPR), dissociative adsorption of nitrous oxide, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Characterization of the RHA-supported copper catalysts (Cu/RHA) indicates that the formation of the copper hydrosilicate with structural properties similar to the mineral chrysocolla. The thermal decomposition of the copper hydrosilicate starts above 673K. Increasing the copper loading, both the calcined and reduced catalysts, causes the specific surface area to rise, and the pore shape of catalysts is changed from “spherical” to “slit-like”. The dispersion of copper decreases with increasing copper loading. The copper surface area increases with copper loading up to 31.0 wt.% and then decreases with further increase in copper loading. Furthermore, the mean size of copper crystallites increases with an increase in copper loading. Moreover, RHA is found to be preferable over silica gel as a support as revealed by the TPR and dissociative adsorption of N2O.
