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Preparation of Sorbents Modified by Metallic Ion and Their Performance of Removing Thiophene in Coking Benzene

Author: ZhangYanJun
Tutor: ChangLiPing
School: Taiyuan University of Technology
Course: Chemical processes
Keywords: Coking Benzene Thiophene Desulfurization Adsorption γ-Al2O3 Zeolite
CLC: TQ522.6
Type: Master's thesis
Year: 2011
Downloads: 80
Quote: 2
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Abstract

Benzene is an important chemical raw materials, mainly from oil and coking industry. In recent years, chemical companies rapid development, expanding the scale of production of downstream products such as styrene, phenol, and led to our continued growth in demand for benzene. The relative shortage of oil resources, relatively rich in coal resources, the rapid development of the coking industry, along with a large number of coking benzene production. Coking benzene in the presence of a certain amount of thiophene sulfides, which will not only corrode metal equipment, cause catalyst poisoning in subsequent production applications, and may lead to environmental pollution, severely limits the coking benzene further processing and utilization. To this end, the national standard on more and more high the coking benzene sulfide content requirements. Adsorption Removal Thiophene Sulfide is a desulfurization method developed in recent years, the method has the advantages of mild reaction conditions, investment costs, the effect of desulfurization and recyclable thiophene adsorbent renewable and less environmental pollution. From energy conservation and environmental protection and resources to take full advantage of the perspective, the assay is a very promising desulfurization applications. But the presence of the selectivity of the adsorbent and sulfur contents smaller shortcomings, the research and development of high performance adsorbents for industrial applications. Based on this, the thesis of thiophene in benzene removal with adsorbent Preparation and Metal Ions conditions were optimized and desulfurization performance were investigated, the key findings are as follows. 1) γ-Al2O3 load metal ion modified adsorbent gamma-Al2O3 is a porous material, the inner surface area of ??up to hundreds of square meters per gram, has a good adsorption properties and thermal stability, cheap and easy to obtain, and the structure is relatively help in the experiments on the study of the adsorption mechanism. First, selection of γ-Al2O3 as carrier volume impregnation method load metal element system to take a series of modified sorbent, and examine its removal thiophene performance, found that the silver nitrate solution load modified obtained adsorption adsorption properties of the agent. Although the impregnation method can accurately control the amount of load of the active ingredient, but there is the problem of uneven distribution of the active component is dispersed. And ultrasonic cavitation can be improved interphase mass transfer rate, changing the the adsorption phase relations, thereby improving the dispersibility of the active ingredient. In view of this, experiments using ultrasound-assisted optimization improvements on conventional impregnation method. The experimental results showed that ultrasound assisted not only shorten the time of the preparation of the adsorbent, but also to enrich the pore structure of the adsorbent refinement Ag particles of the active ingredient to make it uniform distribution, is conducive to the adsorbent for the removal of thiophene. The adsorbent Ag content can be changed to cause the pore structure of the sorbent and the specific surface area changes, and thus impact the desulfurization effect of the adsorbent, ultrasound-assisted impregnation prepared Ag content of 15% of the adsorbent, the adsorption thiophene effect Best. At room temperature, atmospheric pressure, the agent liquid ratio of 1:4 (g / mL), the thiophene concentration is reduced from 500 mg / L to 1.7 mg / L, and the desulfurization efficiency is higher than 99%. The thiophenecarboxylic - benzene, thiophene - cyclohexane, tetrahydrothiophene - benzene, tetrahydrothiophene - cyclohexane four solutions adsorption experimental results show that the Ag modified y-A1203 type adsorbent removal thiophene mainly Ag with two mechanism the thiophene rings Wu complexation and the bond with the sulfur atom. 2) Y-type zeolite metal ion exchange modified adsorbents Y zeolite having a mesh crystal structure of the aluminosilicate has a uniform pore structure and bugholes, and has a large specific surface area and good thermal stability, selectivity adsorption ability, can be used for the separation of different types of molecules. Of the NaY Zeolite metal ion exchange modified, Thiophene in Benzene adsorption desulfurization performance can be significantly improved. Wherein the desulfurization effect of the cerium ion-modified obtained CeY zeolite Preferably, the best preparation conditions modified as follows: 0.1 mol / L of cerium nitrate solution was heated to reflux for ion-exchanged for 4 h, and then in a muffle furnace. 700 ℃ calcined for 2 h, repeated twice ion exchange. Obtained best adsorbents at room temperature, atmospheric pressure, the agent liquid ratio of 1:4 (g / mL), the concentration of the thiophene can be 500 mg / L of thiophene - complete removal of benzene solution of thiophene; agent solution ratio of 1:14 when the desulfurization efficiency of 51.7%, the amount of adsorption becomes saturated, the the equilibrium sulfur capacity of 5.74 mg / g. To filter out static desulfurization experiments the best modified CeY molecular sieve as adsorbent fixed bed adsorption properties of the following experimental results. The smaller the particle size of the adsorbent, the more favorable the adsorption, but particle size is too small may increase the mass transfer resistance between the bed, increasing the energy consumption. The solution flow 0.2ml/min when Preferably, the flow rate is too large or too small will penetrate a shorter time. The adsorption reaction can be conducted at room temperature and high temperatures may weaken the force between the adsorbent with the thiophene, so that the adsorption performance degradation. The adsorption method is more applicable to the removal of the low concentration of thiophene, when thiophene concentration was 200 mg / L, the sulfur capacity of the adsorbent for the 4.18 mg / g, and the processing volume of 20.91 mL / g.

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