不同晶粒尺寸H-ZSM-5催化劑上甲醇芳構化反應性能（英文）
發(fā)布時間：2019-01-27 14:26
【摘要】：芳烴是一類重要的有機化工基礎原料,通常采用傳統(tǒng)的石油路線生產芳烴,包括催化裂化和催化重整等工藝.由于石油資源的緊缺,以可再生資源為原料生產芳烴工藝的發(fā)展具有十分重要的意義.甲醇作為一種重要的基礎原料,可來源于煤、天然氣和生物質等,因此,甲醇制芳烴工藝(MTA)的研究受到日益關注.ZSM-5分子篩具有較大的比表面積、可調節(jié)的酸性、優(yōu)良的擇形選擇性和很高的水熱穩(wěn)定性,因而在甲醇芳構化中展現(xiàn)出良好的催化性能.研究發(fā)現(xiàn),甲醇轉化率和產物分布與ZSM-5分子篩的酸性和多孔性等密切相關.本文通過調控模板劑與水的比例和晶化時間,采用水熱法制備了一系列不同晶粒度H-ZSM-5分子篩催化劑,通過X射線衍射(XRD)、掃描電鏡(SEM)、N_2物理吸附脫附(BET)和X射線熒光光譜等技術對所得分子篩的理化性質、骨架結構和形貌進行了表征;采用吡啶紅外光譜和NH_3程序升溫脫附技術對其酸性進行了分析,使用熱重(TG)技術對反應后催化劑的積碳含量進行了分析,并將所制備的H-ZSM-5分子篩催化劑分別應用于MTA反應,系統(tǒng)性地探究分子篩晶粒度對其理化性質和MTA催化性能的影響.XRD結果表明,所合成的五種樣品均具有典型的ZSM-5分子篩特征衍射峰且無雜晶,且具有不同的晶粒度,分別為4.0±0.3,1.2±0.2μm,614.1±31.9、391.9±32.4和99.1±7.0 nm.N_2物理吸附脫附曲線可以發(fā)現(xiàn),晶粒度為99.1±7.0 nm的ZSM-5分子篩展現(xiàn)出典型的Ⅰ型和Ⅳ型物理吸附曲線且在較高的相對壓力(p/p_0=0.8-1.0)處有一個明顯的H4型遲滯環(huán),表明此分子篩具有介孔和大孔結構;BJH吸附孔徑分布圖表明,這些介孔主要分布在2-7和20-50 nm范圍內;同時各樣品的比表面積和孔體積隨著其晶粒度的減小而增大.結果還表明五種不同晶粒度的ZSM-5分子篩具有相似的SiO_2/Al_2O_3摩爾比和酸性質.MTA反應結果表明,隨著催化劑晶粒度的降低,甲醇的平均轉化率,芳烴選擇性和BTX選擇性有所提高,在300 min時晶粒度較大的三個催化劑上,甲醇轉化率迅速降至90%,而晶粒度較小的兩個催化劑上,甲醇轉化率始終維持在95%以上,其中晶粒度為99.1±7.0 nm的樣品上芳烴選擇性最高(平均42%以上),BTX選擇性達37%.對失活催化劑積碳含量分析,隨著催化劑晶粒度的降低,積碳量降低.晶粒度較低的納米分子篩催化劑具有更短的孔道,更高效的擴散性能,更高的比表面積和獨特的梯級孔結構,因而在甲醇芳構化反應中展現(xiàn)出更長的壽命,更高的活性和更低的積碳量,在甲醇制芳烴工業(yè)化生產中具有巨大潛力.
[Abstract]:Aromatics are a kind of important organic chemical raw materials, which usually produce aromatics by traditional petroleum route, including catalytic cracking and catalytic reforming. Because of the shortage of petroleum resources, it is very important to develop the process of producing aromatics from renewable resources. As an important basic raw material, methanol can be derived from coal, natural gas and biomass. Therefore, the study of methanol to aromatics process (MTA) has attracted increasing attention. ZSM-5 molecular sieve has a large specific surface area and adjustable acidity. Because of its excellent shape selectivity and high hydrothermal stability, it exhibits good catalytic performance in methanol aromatization. It was found that methanol conversion and product distribution were closely related to the acidity and porosity of ZSM-5 molecular sieves. In this paper, a series of H-ZSM-5 molecular sieve catalysts with different crystal sizes were prepared by hydrothermal method by adjusting the ratio of template to water and crystallization time. The (SEM), was obtained by (XRD), scanning electron microscope (SEM). The physicochemical properties, skeleton structure and morphology of the molecular sieve were characterized by physical adsorption and desorption of N-2 by (BET) and X-ray fluorescence spectroscopy. The acidity of the catalyst was analyzed by pyridine infrared spectroscopy and NH_3 temperature programmed desorption, and the carbon content of the catalyst was analyzed by thermogravimetric (TG). The H-ZSM-5 molecular sieve catalysts were used in MTA reaction, and the effects of molecular sieve grain size on their physicochemical properties and catalytic properties of MTA were systematically investigated. The results of XRD showed that, The five samples were characterized by typical diffraction peaks of ZSM-5 molecular sieve, no heterocrystals, and different grain sizes, which were 4.0 鹵0.3 鹵1.2 鹵0.2 渭 m, respectively. The physical adsorption and desorption curves of 614.1 鹵31.9391.9 鹵32.4 and 99.1 鹵7.0 nm.N_2 can be found. ZSM-5 molecular sieves with a grain size of 99.1 鹵7.0 nm exhibit typical physical adsorption curves of type 鈪，
本文編號：2416351
[Abstract]:Aromatics are a kind of important organic chemical raw materials, which usually produce aromatics by traditional petroleum route, including catalytic cracking and catalytic reforming. Because of the shortage of petroleum resources, it is very important to develop the process of producing aromatics from renewable resources. As an important basic raw material, methanol can be derived from coal, natural gas and biomass. Therefore, the study of methanol to aromatics process (MTA) has attracted increasing attention. ZSM-5 molecular sieve has a large specific surface area and adjustable acidity. Because of its excellent shape selectivity and high hydrothermal stability, it exhibits good catalytic performance in methanol aromatization. It was found that methanol conversion and product distribution were closely related to the acidity and porosity of ZSM-5 molecular sieves. In this paper, a series of H-ZSM-5 molecular sieve catalysts with different crystal sizes were prepared by hydrothermal method by adjusting the ratio of template to water and crystallization time. The (SEM), was obtained by (XRD), scanning electron microscope (SEM). The physicochemical properties, skeleton structure and morphology of the molecular sieve were characterized by physical adsorption and desorption of N-2 by (BET) and X-ray fluorescence spectroscopy. The acidity of the catalyst was analyzed by pyridine infrared spectroscopy and NH_3 temperature programmed desorption, and the carbon content of the catalyst was analyzed by thermogravimetric (TG). The H-ZSM-5 molecular sieve catalysts were used in MTA reaction, and the effects of molecular sieve grain size on their physicochemical properties and catalytic properties of MTA were systematically investigated. The results of XRD showed that, The five samples were characterized by typical diffraction peaks of ZSM-5 molecular sieve, no heterocrystals, and different grain sizes, which were 4.0 鹵0.3 鹵1.2 鹵0.2 渭 m, respectively. The physical adsorption and desorption curves of 614.1 鹵31.9391.9 鹵32.4 and 99.1 鹵7.0 nm.N_2 can be found. ZSM-5 molecular sieves with a grain size of 99.1 鹵7.0 nm exhibit typical physical adsorption curves of type 鈪，
本文編號：2416351
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