Modification And Evaluation Of The Catalyst For N-butane Isomerization

Modification,characterization and evaluation of high-performance catalyst was system-atically studied in this paper. The suitable condition of modification was determined. The yield of i-butane for n-butane isomerization was improved effectively.The H-Mordenite, as the carrier of the catalyst,was treated in different acid solution and different alkaline. Suitable conditions for n-butane isomerization are obtained. Acid treating, alkaline treating and a series of different concentration of Na OH alkaline solution treating were used for the modification of H-Mordenite respectively.The crystallinity,surface area, and the changes in structural and acidic properties were investigated with the X-ray diffraction,Py-IR, and N2 adsorption-desorption isotherms. Additionally,The yield of i-butane for n-butane isomerization per unit time was successfully improved by the addition of Sn.The experimental results of using oxalic acid, citric acid, phosphoric acid, hydrochloric acid under the same conditions showed that the crystallinity of the H-mordenite was affected significantly. Oxalic acid made the most serious erosion to the H-mordenite. The BET results showed that the mesopore size of the H-mordenite after treating increased in different degrees, The yiled of i-butane over the catalyst of different modified H-mordenite supported 0.38%Pt,to different extents,were improved. Especially,the yield of i-butane for n-butane isomerization per unit time over the Pt-HM-H3PO4 was improved by 10 %.Also, the H-Mordenite was treated in different alkaline solution, just as potassium hydroxide(KOH), ammonia solution(NH3·H2O), sodium carbonate solution(Na2CO3), sodium hydroxide solution(Na OH), and a series of different concentration of NaOH alkaline solution. It was found that the yield over the catalyst which was treated in 0.2 mol·L-1 sodium hydroxide solution was improved by 11 %, compared with Pt-HM. Suitable pore structure and specific surface area are beneficial for the yield of i-butane.Adding Sn as metal promoter iron in the ratio of the amount of substance(Sn / Pt=1,2,3) to the catalyst has little effect on the activity and the mesopore size of the prepared catalysts,but it could raise the conversions rate effectively when Sn / Pt=2.It was found that the selectivity of i-butane was improved by 3 % and the yiled of i-butane per unit time was improved by 5 % respectively.