工业生产过程中产生大量粉煤灰、赤泥和煤气化渣,其堆积不仅侵占土地,还会严重破坏生态环境,危及人类健康。这3种固废均含有硅铝元素,且含量较高,硅铝比(氧化硅和氧化铝物质的量比)波动幅度较大。ZSM-5(Zeolite Socony Mobil 5)是一类...工业生产过程中产生大量粉煤灰、赤泥和煤气化渣,其堆积不仅侵占土地,还会严重破坏生态环境,危及人类健康。这3种固废均含有硅铝元素,且含量较高,硅铝比(氧化硅和氧化铝物质的量比)波动幅度较大。ZSM-5(Zeolite Socony Mobil 5)是一类硅铝比范围较宽的沸石分子筛,具有独特的孔道结构和良好的稳定性,在吸附和催化方面应用广泛。利用富含硅铝的固废制备ZSM-5是其高值化和资源化利用的重要途径之一。系统总结了富含硅铝的固废的活化除杂预处理通用方法,并且基于粉煤灰、赤泥和煤气化渣的理化性质特点,综述了固废基ZSM-5的合成及金属改性、磷改性、水热改性和酸碱改性4种方法的研究进展。分析固废作为硅铝源对ZSM-5合成、结构和性能的影响,指出固废在活化除杂过程中硅铝比的调控、杂质元素的去除转化、及主要元素的迁移转化规律是研究重点;讨论不同改性方法对ZSM-5结构和性能的影响机制,提出固废基ZSM-5中硅铝在骨架和非骨架中的分布、铁钙等杂元素的含量和存在形态、孔结构对改性效果起到非常重要的作用。通过对典型富含硅铝元素的固废基ZSM-5合成及其改性过程中存在问题和研究现状的分析和讨论,提出了粉煤灰、赤泥和煤气化渣多源固废复配,在无机模板剂或无模板剂条件下水热晶化制备ZSM-5,对固废基ZSM-5高效精准改性是未来发展方向。展开更多
The ZSM-5 zeolite with an unusual snowflake-shaped morphology was hydrothermally synthesized for the first time,and compared with common ellipsoidal and boat-like shaped samples.These samples were characterized by N2 ...The ZSM-5 zeolite with an unusual snowflake-shaped morphology was hydrothermally synthesized for the first time,and compared with common ellipsoidal and boat-like shaped samples.These samples were characterized by N2 adsorption-desorption,X-ray fluorescence spectroscopy,scanning electron microscopy,X-ray diffraction,magic angle spinning nuclear magnetic resonance,temperature-programmed desorption of ammonia,and infrared spectroscopy of pyridine adsorption.The results suggest that the BET surface area and SiO2/Al2O3 ratio of these samples are similar,while the snowflake-shaped ZSM-5 zeolite possesses more of the（101） face,and distortion,dislocation,and asymmetry in the framework,resulting in a larger number of acid sites than the conventional samples.Catalysts for the methanol to olefin（MTO） reaction were prepared by loading Ca on the samples.The snowflake-shaped Ca/ZSM-5 zeolite exhibited excellent selectivity for total light olefin（72%） and propene（39%） in MTO.The catalytic performance influenced by the morphology can be mainly attributed to the snowflake-shaped ZSM-5 zeolite possessing distortion,dislocation,and asymmetry in the framework,and lower diffusion limitation than the conventional samples.展开更多
The promoting effect of introducing Zn into nano-ZSM-5 zeolites by conventional impregnation method and isomorphous substitution on the performance of 1-hexene aromatization was investigated. The nano-ZSM-5 zeolite wa...The promoting effect of introducing Zn into nano-ZSM-5 zeolites by conventional impregnation method and isomorphous substitution on the performance of 1-hexene aromatization was investigated. The nano-ZSM-5 zeolite was synthesized by a seed-induced method without organic templates. The Zn-modified nano-ZSM-5 zeolite catalysts, xZ n/HNZ5 and y Zn/Al-HNZ5, were prepared by the conventional impregnation method and isomorphous substitution, respectively. The structure, chemical composition and acidity of the catalysts were characterized by XRD, XRF, N2 adsorption, SEM, NH3-TPD and Py-IR, while the catalytic properties were evaluated at 480 °C and a weight hourly space velocity（WHSV） of 2.0 h-1 in the aromatization procedure of 1-hexene. Compared with xZ n/HNZ5, y Zn/Al-HNZ5 exhibited smaller particles and higher dispersion of Zn species, which led to greater intergranular mesopore and homogeneous acidity distribution. Experimental results indicated that the synergy effect between the Brnsted and Lewis acid sites of the isomorphously substituted nano-ZSM-5 zeolites could significantly increase aromatics yield and improve catalytic stability in the 1-hexene aromatization.展开更多
文摘工业生产过程中产生大量粉煤灰、赤泥和煤气化渣,其堆积不仅侵占土地,还会严重破坏生态环境,危及人类健康。这3种固废均含有硅铝元素,且含量较高,硅铝比(氧化硅和氧化铝物质的量比)波动幅度较大。ZSM-5(Zeolite Socony Mobil 5)是一类硅铝比范围较宽的沸石分子筛,具有独特的孔道结构和良好的稳定性,在吸附和催化方面应用广泛。利用富含硅铝的固废制备ZSM-5是其高值化和资源化利用的重要途径之一。系统总结了富含硅铝的固废的活化除杂预处理通用方法,并且基于粉煤灰、赤泥和煤气化渣的理化性质特点,综述了固废基ZSM-5的合成及金属改性、磷改性、水热改性和酸碱改性4种方法的研究进展。分析固废作为硅铝源对ZSM-5合成、结构和性能的影响,指出固废在活化除杂过程中硅铝比的调控、杂质元素的去除转化、及主要元素的迁移转化规律是研究重点;讨论不同改性方法对ZSM-5结构和性能的影响机制,提出固废基ZSM-5中硅铝在骨架和非骨架中的分布、铁钙等杂元素的含量和存在形态、孔结构对改性效果起到非常重要的作用。通过对典型富含硅铝元素的固废基ZSM-5合成及其改性过程中存在问题和研究现状的分析和讨论,提出了粉煤灰、赤泥和煤气化渣多源固废复配,在无机模板剂或无模板剂条件下水热晶化制备ZSM-5,对固废基ZSM-5高效精准改性是未来发展方向。
基金Synfuels China Co.Ltd.for the financial and equipments support
文摘The ZSM-5 zeolite with an unusual snowflake-shaped morphology was hydrothermally synthesized for the first time,and compared with common ellipsoidal and boat-like shaped samples.These samples were characterized by N2 adsorption-desorption,X-ray fluorescence spectroscopy,scanning electron microscopy,X-ray diffraction,magic angle spinning nuclear magnetic resonance,temperature-programmed desorption of ammonia,and infrared spectroscopy of pyridine adsorption.The results suggest that the BET surface area and SiO2/Al2O3 ratio of these samples are similar,while the snowflake-shaped ZSM-5 zeolite possesses more of the（101） face,and distortion,dislocation,and asymmetry in the framework,resulting in a larger number of acid sites than the conventional samples.Catalysts for the methanol to olefin（MTO） reaction were prepared by loading Ca on the samples.The snowflake-shaped Ca/ZSM-5 zeolite exhibited excellent selectivity for total light olefin（72%） and propene（39%） in MTO.The catalytic performance influenced by the morphology can be mainly attributed to the snowflake-shaped ZSM-5 zeolite possessing distortion,dislocation,and asymmetry in the framework,and lower diffusion limitation than the conventional samples.
基金Project(21276067)supported by the National Natural Science Foundation of China
文摘The promoting effect of introducing Zn into nano-ZSM-5 zeolites by conventional impregnation method and isomorphous substitution on the performance of 1-hexene aromatization was investigated. The nano-ZSM-5 zeolite was synthesized by a seed-induced method without organic templates. The Zn-modified nano-ZSM-5 zeolite catalysts, xZ n/HNZ5 and y Zn/Al-HNZ5, were prepared by the conventional impregnation method and isomorphous substitution, respectively. The structure, chemical composition and acidity of the catalysts were characterized by XRD, XRF, N2 adsorption, SEM, NH3-TPD and Py-IR, while the catalytic properties were evaluated at 480 °C and a weight hourly space velocity（WHSV） of 2.0 h-1 in the aromatization procedure of 1-hexene. Compared with xZ n/HNZ5, y Zn/Al-HNZ5 exhibited smaller particles and higher dispersion of Zn species, which led to greater intergranular mesopore and homogeneous acidity distribution. Experimental results indicated that the synergy effect between the Brnsted and Lewis acid sites of the isomorphously substituted nano-ZSM-5 zeolites could significantly increase aromatics yield and improve catalytic stability in the 1-hexene aromatization.
