问题 问答题 简答题

什么叫催化剂结焦?如何防止?

答案

参考答案:

催化剂使用过程中,反应系统中某些组分的分子经脱氢聚合形成高聚物,进而脱氢形成氢含量很低的焦类物质沉积在催化剂表面,减少可利用的表面积,同时由于孔口堵塞,降低了内表面利用率,引起活性衰退,这种现象称为结焦,降低了内表面利用率。引起活性衰退,这种现象称为结焦,结焦是催化剂失活最普遍的形式,可以再生,因此是一个可逆过程。

防止催化剂结焦应从以下几方面做工作:

①控制好原料的密度、干点、比色等指标,防止胶质、沥青质的大量带入。

②保持在较高的氢油比下操作,抑制结焦反应。

③严防催化剂超温。

阅读理解

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Among the four skills in learning English, which of these is the “Odd-Man-Out”? The answer is speaking. The other three you can do alone on your own. But you can't really speak alone! Speaking to yourself can be “dangerous” because men in white coats may come and take you away !

Where can you find people to speak English? And how can you practise speaking when you are alone? At school if you pay to go to a language school, you should use the chance to speak .If your teacher asks you to speak in pairs or groups with other students, try to say as much as possible. Don't worry about your mistakes. Just speak!

Conversation Clubs Many cities around the world have conversation clubs where people can exchange one language for another . Look in your local newspaper to find a conversation club near you .They are usually free although some may charge a small entrance fee.

Shopping Even if you don't want to buy anything ,you can ask questions about products that interest you in a shop. “How much does this cost?” “Can I pay by cheque?” Often you can start a real conversation—and it costs you nothing!

Cafe and Bars There are often American, Britain, Irish and Australian bars in many large cities .If you can find one, you'll probably meet many people speaking English as a first or second language.

Language is all around you Everywhere you go, you find language .Shop names, street names ,advertisements ,notices ,and car numbers....When you walk down the street , practice reading the words and numbers that you see .Say them to yourself .It's not exactly a conversation ,but it will help you to “think” in English .But don't speak too loud!

Songs and Video Repeat the words of an English-language song singing with the music until it becomes automatic. It's good practice for your memory and for the mouth muscles that you need for English.

Above all, speak as much as possible! Make as many mistakes as possible! When you know that you have made a mistake, you know that you have made progress!

57.What does “Odd-Man-Out” probably mean according to the passage?

A. Someone or something appearing different from others.

B. Someone or something standing out of the group.

C. Someone or something arranged in pairs.

D. Someone or something easily mistaken for another.

58.What might happen if you speak to yourself loudly in public?

A. The police will take you away and punish you.

B. The doctors will force you to stay in hospital.

C. You will have to pay to escape being punished.

D. You will be forbidden to be member of the club.

59.Why does the writer say “Make as many mistakes as possible”? Because _______.

A. everyone will make mistakes in learning English

B. everyone will meet people speaking English with some mistakes

C. making mistakes is a must in making progress in learning English

D. making mistakes can make one realize the importance of speaking

60.According to the passage, which way is not likely to be accepted by English beginners?

A .Recite poems loudly along the riverside.

B. Listen to some English pop songs and video.

C. Find an Englishman to speak English with.

D. Take to the TV showing programmes at home.

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