Tips and Examples for Writing Thesis Statements
This resource provides tips for creating a thesis statement and examples of different types of thesis statements.
Contributors: Elyssa Tardiff, Allen Brizee
Last Edited: 2018-01-24 02:29:37
Tips for Writing Your Thesis Statement
1. Determine what kind of paper you are writing:
- An analytical paper breaks down an issue or an idea into its component parts, evaluates the issue or idea, and presents this breakdown and evaluation to the audience.
- An expository (explanatory) paper explains something to the audience.
- An argumentative paper makes a claim about a topic and justifies this claim with specific evidence. The claim could be an opinion, a policy proposal, an evaluation, a cause-and-effect statement, or an interpretation. The goal of the argumentative paper is to convince the audience that the claim is true based on the evidence provided.
If you are writing a text that does not fall under these three categories (e.g., a narrative), a thesis statement somewhere in the first paragraph could still be helpful to your reader.
2. Your thesis statement should be specific—it should cover only what you will discuss in your paper and should be supported with specific evidence.
3. The thesis statement usually appears at the end of the first paragraph of a paper.
4. Your topic may change as you write, so you may need to revise your thesis statement to reflect exactly what you have discussed in the paper.
Thesis Statement Examples
Example of an analytical thesis statement:
An analysis of the college admission process reveals one challenge facing counselors: accepting students with high test scores or students with strong extracurricular backgrounds.
The paper that follows should:
- Explain the analysis of the college admission process
- Explain the challenge facing admissions counselors
Example of an expository (explanatory) thesis statement:
The life of the typical college student is characterized by time spent studying, attending class, and socializing with peers.
The paper that follows should:
- Explain how students spend their time studying, attending class, and socializing with peers
Example of an argumentative thesis statement:
High school graduates should be required to take a year off to pursue community service projects before entering college in order to increase their maturity and global awareness.
The paper that follows should:
- Present an argument and give evidence to support the claim that students should pursue community projects before entering college
The vapor mixture is sent to the reactor tube side which is packed with the solid phosphoric acid catalyst supported on the kieselguhr the exothermal heat is removed by the pressurized water which is used for steam production and the effluent from the reactor i.e., cumene, p-DIPB, unreacted benzene, propylene and propane with temperature 350oC is used as the heating media in the vaporizer which used for the benzene vaporizing and cooled to 40oC in a water cooler, propylene and propane are separated from the liquid mixture of cumene, p-DIPB, benzene in a separator operating slightly above atm and the pressure is controlled by the vapor control value of the separator, the fuel gas is used as fuel for the furnace also.
The liquid mixture is sent to the benzene distillation column which operates at 1 atm pressure, 98.1% of benzene is obtained as the distillate and used as recycling and the bottom liquid mixture is pumped at bubble point to the cumene distillation column where distillate 99.9% cumene and bottom pure p-DIPB is obtained. The heat of bottom product p-DIPB is used for preheating the benzene column feed, All the utility as cooling water, electricity, steam from the boiler, pneumatic air are supplied from the utility section
Disadvantages of using solid phosphoric acid (SPA) Process
1. Lower activity
2. Catalyst non-regenerability
3. Unloading of spent catalyst from reactor difficult
4. Relative high selectivity to hexyl benzene
5. Significant yield of DIPB
Disadvantages of using Aluminum chloride as catalyst
1. High corrosion
2. Environmental hazard
3. Washing step for catalyst removal
Modern Industrial Cumene Production Process:Cumene is an important chemical in the present industrial world and its uses are steadily increasing. The process followed for the production of cumene is the catalytic alkylation of benzene with propylene and nowadays zeolite based catalysts are used in place of the normal acid based catalysts due to added advantages. Cumene production process has been greatly studied and the reaction mechanism and the reaction kinetics have been specified by many researchers. Both experimental, as well as computer-based simulation and optimization studies, have been carried out by various researchers.
Q-MAX™ Process Description for cumene production:
The Q-MAX™ process provides a very good cumene yield and quality. The QZ-2000 zeolite-based catalyst utilized for the Q-MAX™ process which operates with a low flow rate of benzene and hence investment and utility costs are reduced greatly. QZ-2000 is non-corrosive and regenerate-able. Compared to other zeolite based cumene technologies, the QMAX ™ process provides the highest product quality and great stability. Impurities in the fee have less effect
The alkylation reactor is divided into four catalytic beds present in a single reactor shell.The fresh benzene feed is passed through the upper-mid section of the depropanizer column to remove excess water and then sent to the alkylation reactor. The recycle benzene to the alkylation and transalkylation reactors is drawn from the benzene column. This mixture of fresh and recycle benzene is charged through the alkylation reactor. The fresh propylene feed is split between the catalyst beds and is fully consumed in each bed. An excess of benzene helps in avoiding the formation of poly alkylation and reduce the effect of olefin oligomerization.
As the chemical reaction occurs at the exothermic condition, the temperature increase during the alkylation reaction is controlled by the reactor effluent. The temperature of inlet stream from the catalyst beds is further maintained to the designed temperature by the circuit reactor effluent passing tubes which are cooled by the side stream heat exchangers between the beds. Reacted effluent from the chemical reactor is fed to the depropanizer column which separates the propane and excess water. The bottoms stream of the depropanizer column is fed to the benzene distillation column where excess benzene is collected at top of the column and recycled to the process feed stream.
The benzene distillation column bottom stream fed to the cumene rectifying column where cumene is recovered overhead. The cumene rectifying column bottom product is diisopropylbenzene (DIPB), and fed to the DIPB rectifying column. The DIPB stream is recycled to increase the conversion to the transalkylation reactor. The DIPB column bottom products contain of heavy aromatic by-products, which are blended into fuel oil. High-pressure steam is used as the heating medium to the fractionation columns.
The recycle DIPB from the overhead of the DIPB column combines with a portion of the recycle benzene and is charged downflow through the transalkylation reactor. In the transalkylation reactor, DIPB and benzene are converted to more cumene. The effluent from the transalkylation reactor is then sent to the benzene column. The new QZ-2001 catalyst is utilized in the alkylation reactor while the original QZ-2000 catalyst used for the transalkylation reactor. Catalyst lifetime is about 2–4 years.
The Q-Max™ process typically produces near equilibrium levels of cumene (between 85 and 95 mol %) and DIPB (between 5 and 15 mol %). The DIPB is separated from the cumene and is reacted with recycling benzene at optimal conditions for transalkylation to produce additional cumene.
Reaction Mechanism and Kinetics for Cumene Production:
The following reaction mechanism is proposed for the alkylation of benzene for production of cumene. The major reactions taking place are alkylation and trans-alkylation. Side reactions which take place are isomerisation and dis-proportionation. The reaction mechanism and kinetics may vary depending on the catalyst used. The reaction can occur in presence or absence of carbonium ion intermidate.
The reation kinetic data is obtained based on the specific catalyst used for the reaction, for example, phosphoric acid catalyst and the reaction,
Propylene + Benzene→ Cumene
Specific Rate constant= k= 2.8X10^7
Activation energy = E = 104174 KJ/kmol
Rate of reaction = specific rate constant X Concentration of Benzene and Propylene
= k .Cb Cp
The reaction rate constant k = 6.52 X 10-3 exp(27240/RT)
This equilibrium data for the trans-alkylation reaction is obtained for modified Zeolite beta catalyst.