HPA/TiO2-WO3催化合成乙酸环己酯的研究

以乙酸和环己醇为原料，采用纳米固载型杂多酸HPA／TiO2-WO3为催化剂，系统研究了合成乙酸环己酯的优化条件．优化条件为：乙酸0．108mol，环己醇0．06mol，催化剂0．3g，反应时间90min，乙酸环己酯收率为84．7％．     

酯合成反应中的新型催化剂

综述了酯合成反应中的新型催化剂如超强酸固体催化剂、固载杂多酸催化剂、Lewis酸催化剂、固体稀土超强酸催化剂等的研究进展。     

固载杂多酸TiGeW12O40／TiO2的合成、表征及催化活性

报道了固载杂多酸TiGeW12O40/TiO2的制备方法，并用IR、XRD对其结构进行表征，研究了催化剂在酯化反应中的催化作用．     

固载杂多酸的合成、表征及催化异丙醇脱水反应的活性

采用浸渍法制备负载型HPA／MCM－41催化剂，用FT－IR，XRD表征了催化剂的骨架和晶体结构及性能。负载后HPA的酸强度得到了提高，其Keggin结构仍然保持。适量的杂多酸对MCM－41的介孔性质无影响。不同载体与HPA之间的作用不相同。固载化HPA应用于异丙醇气相脱水反应，得到了与表征完全一致的结果。     

纳米催化剂研究进展

纳米材料具有独特的晶体结构及表面特性，其催化活性和选择性大大高于传统催化剂，目前已经被国内外作为第4代催化剂进行研究和开发．介绍了纳米材料的催化特性，综述了纳米金属粒子催化剂、纳米金属氧化物催化剂、纳米半导体粒子、纳米固载杂多酸催化剂、纳米(复合)固体超酸催化剂、磁性纳米固体酸催化剂、碳纳米管及分子筛等的应用进展．指出了纳米催化剂的优势及目前存在的问题．     

增塑剂邻苯二甲酸二异辛酯的催化合成研究进展

综述了固体超强酸、无机盐、铌酸及固载杂多酸、钛酸四丁酯、对甲苯磺酸等催化剂催化合成邻苯二甲酸二异辛酯(DIOP)的方法.通过比较发现硫酸氢钠具有催化效果好、用量少、反应时间短、酯化率高和环境污染小等优点.     

固载杂多酸催化合成苯甲酸乙酯

在固载杂多酸PW1 2 SiO2 催化剂存在下 ,由苯甲酸与乙醇反应合成苯甲酸乙酯。最佳合成条件为 :n(酸 ) :n(醇 ) =1∶4 .0 ,催化剂用量为苯甲酸质量的 10 % ,反应时间为 5h ,产率可达 91%。催化剂具有容易回收并可循环使用、不污染环境等优点     

固载硅钨杂多酸催化合成戊二酸二异辛酯研究

研究了活性炭固载杂多酸催化戊二酸和异辛醇合成戊二酸二异辛酯的反应,探讨了原料配比、反应时间、催化剂用量等对酯化率的影响,当温度为120℃,醇酸摩尔比为2．5：1,反应时间为2h,催化剂用量为系统总质量的0．5％时,酯化率可达97．8％．     

固载杂多酸催化合成肉桂酸异戊酯

用固载杂多酸PW12 /SiO2 为催化剂 ,实现了肉桂酸与异戊醇反应合成肉桂酸异戊酯。最佳合成条件为 :n(酸 ) :n(醇 ) =1:2 ,催化剂用量为肉桂酸质量的 5 % ,反应时间为 3h ,产率可达 95 %。催化剂具有容易回收并可循环使用、不污染环境等优点。     

活性炭固载磷钨杂多酸催化合成苯乙酸乙酯

以活性炭固载磷钨杂多酸为催化剂,苯乙酸和乙醇为原料合成苯乙酸乙酯,考察了影响反应的因素。结果表明,反应温度为80～85℃时,n(醇)∶n(酸)=3.5∶1;催化剂用量为1.0g(苯乙酸为0.05mol的情况下);反应时间为4.5h是最适宜的反应条件。酯化率可达92.5%。     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

Western and Eastern culture differences in commercial field

The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity.     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

风的曲线

Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose.     

团图为数的图中的闭团贯数

Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.