Styrene epoxidation with hydrogen peroxide over calcium oxide catalysts prepared from various precur

来源 :Journal of Natural Gas Chemistry | 被引量 : 0次 | 上传用户:a27155908
下载到本地 , 更方便阅读
声明 : 本文档内容版权归属内容提供方 , 如果您对本文有版权争议 , 可与客服联系进行内容授权或下架
论文部分内容阅读
A series of CaO samples were prepared by calcination of commercially available and synthesis of calcium salt precursors such as calcium acetate,carbonate,hydroxide and oxalate etc.CaO samples were found to be effective for the epoxidation of styrene using hydrogen peroxide as an oxidant in the presence of acetonitrile.To determine the influence of the physicochemical properties and surface basicity on the catalytic activity,the prepared CaO samples were characterized using thermogravimetry(TG),X-ray diffraction(XRD),scanning electron microscopy(SEM),N2-adsorption and temperature-programmed desorption of CO2(CO2-TPD).The results indicate that the amounts of very strong basic sites and high basicity strength on CaO sample are key factors for its excellent catalytic performance.In contrast,the surface area,porosity and the surface structure of CaO sample have a relatively minor effect on the catalytic activity.CaO sample,obtained by the decomposition of Ca(OH)2,prepared by precipitating calcium nitrate with sodium hydroxide in ethylene glycol solution,exhibits the highest amount of very strong basic sites and stronger strength of basic sites,and therefore it catalyses the epoxidation of styrene with the highest rate among the tested CaO samples.Under the selected reaction conditions,the selectivity of 97.5% to styrene oxide at a conversion in excess of 99% could be obtained. A series of CaO samples were prepared by calcination of commercially available and synthesis of calcium salt precursors such as calcium acetate, carbonate, hydroxide and oxalate etc. CaO samples were found to be effective for the epoxidation of styrene using hydrogen peroxide as an oxidant in the presence of acetonitrile. To determine the influence of the physicochemical properties and surface basicity on the catalytic activity, the prepared CaO samples were characterized using thermogravimetry (TG), X-ray diffraction (XRD), scanning electron microscopy (SEM) and temperature-programmed desorption of CO2 (CO2-TPD). The results indicate that the amounts of very strong basic sites and high basicity strength on CaO sample are key factors for its excellent catalytic performance. contrast, the surface area, porosity and the surface structure of CaO sample have a relatively minor effect on the catalytic activity. CaO sample, obtained by the decomposition of Ca (OH) 2, prepared by precipitating c alcium nitrate with sodium hydroxide in ethylene glycol solution, exhibits the highest amount of very strong basic sites and strong strength of basic sites, and therefore it catalyses the epoxidation of styrene with the highest rate among the tested CaO samples. Unit of the selected reaction conditions, the selectivity of 97.5% to styrene oxide at a conversion in excess of 99% could be obtained.
其他文献
1.临床资料 本组24例急性有机磷农药中毒,占我院同期收治的急性中毒病人总数的60%,吞服量最小20ml,最多200ml,2例吞服量不详。男性7例,女性17例;年龄最小16岁,最大68岁,以17~3
安眠类药物主要归类于苯二氮 类抗焦虑药。临床主要用于镇静,催眠及抗癫痫。本类药物主要作用于边缘系统(尤其是杏仁核),其次是间脑,而对脑干网状结构作用不大。上述部位,特
中日两国博物馆无论从文化渊源角度,还是从博物馆发展轨迹来看都有诸多相似之处。但是,在相似的外表下也存在一些不为人知的明显的差异。近代以来,伴随着博物馆社会职能的转
在生产和生活中,含碳物质燃烧不完全,都可产生一氧化碳(CO)。如不注意煤气管道的密闭和环境的通风等预防措施,吸入过量CO后可发生一氧化碳中毒。1.病因 CO是无色、无臭、无
当你来到一个陌生的地方想知道自己所处的位置;当你想随时随地获知周边的旅游信息和配套服务;当你想获知下一个目的地的旅游交通信息和最佳旅游方案;当你想随时查看景区的实况,当你想预订酒店、机票及旅游行程,当你想……这一切随着智慧旅游信息服务平台的推出已经逐步成为现实,走进我们的生活。  智慧旅游,也被称为智能旅游,是利用云计算、物联网等新技术,通过互联网、无线网络,借助便携的终端设备,主动感知旅游资源、
患者,男,86岁.因反复发作心悸2天入院.既往有阵发性心动过速病史20余年.体检:血压16/10kPa,神志清楚,呼吸平稳,心率160次/分,律齐,无杂音,心界无扩大,四肢无水肿.心电图(附图
在西方70多年的聚落考古的理论探讨和实践工作中,关于“空间性”的讨论一直是其重要内容。如针对空间分析方法本身、空间分析在聚落考古中的功能、程度及可行性的把握等方面
云阳李家坝遗址是重庆三峡库区一处重要的古文化遗址,汉六朝时期墓葬集中分布地之一是遗址Ⅳ区乌龟包山顶及山腰。共清理18座,有竖穴岩坑墓、石室墓、砖室基三种类型,年代在
患者 男,55岁,因皮肤发黑16年,恶心呕吐5天,神志不清1小时入院。患者于16年前无明显诱因出现纳差,乏力及全身皮肤色素沉着伴消瘦,经检查后诊断为阿狄森氏病,口服强地松替代
经颅彩色多普勒超声对老年糖尿病病人脑血流动力学模拟三维图像研究100853北京解放军总医院王新明,孙红,邵勇中国图书资料分类号R445.1脑血管造影可以显示脑血管内的形态学改变,不能提供其血