1 Experimental part 1.1 Instruments and reagents Magna 750 type Fourier transform infrared spectrometer (KBr tablet). The reagents used were of analytical grade. 1.2 Preparation of SFZ ZrOCl28H2O and Fe(NO3)39H2O are dissolved in a certain amount of distilled water according to a certain ratio, and the coprecipitation reaction (UCOP) is carried out under ultrasonic irradiation with ammonia as a precipitant to control pH89. After aging for 15 hours at 15 hours, the filter cake was washed with distilled water until no Cl- ions were detected. After drying at 120 for 12h, a brown fluffy solid was obtained. After slightly grinding, it was poured into 0.5 mol L-1 sulfuric acid for 4 hours, then drained, and calcined at a specified temperature for 4 hours in a muffle furnace. The cold yellow SFZ was obtained after cooling to room temperature. Experimental conditions of SFZ1SFZ12.
SFZ13SFZ16 was prepared by mechanical stirring coprecipitation method (NCOP for short) as a comparative sample. 1.3 SFZ catalyzed synthesis of n-butyl acetate n (acetic acid) n (n-butanol) = 1.01.2, w (SFZ) = 1.4%, n-butyl acetate was synthesized at 120 h for 2.5 h. IR: 3450, 2962, 2876, 1743 (C = 0), 1466, 1367, 1244, 1056, 1043, 951, 920, 848, 839, 607, 633 (ester) cm-1. The esterification rate was determined according to the method of GB166881. 2 Results and discussion 2.1 Acid strength of SFZ The acid strength of SFZ was tested by the flow Hammett indicator method. It can be seen that the acid strength of SFZ varies with the preparation conditions. At the same calcination temperature, the acid strength of SFZ is n ( When Fe)n(Zr)=11, it is the strongest; when n(Fe)n(Zr) is constant, the acid strength of SFZ is the strongest when calcined at 650; the H0 of SFZ8 with the highest acid strength can reach -16.0, and Under the same conditions, the preparation conditions of H0=-14.5.2.2 prepared by NCOP were compared to the specific surface area of ​​SFZ. The specific surface area of ​​some SFZ was determined by BET method. The results showed that the ratio of SFZ prepared by UCOP method was the same when other conditions were unchanged. The surface area is much larger than the specific surface area of ​​the SFZ produced by the NCOP process.
It can be seen that UCOP can refine the SFZ particles and increase the specific surface area. It can also be seen that as the calcination temperature increases, the specific surface area of ​​SFZ gradually decreases, possibly due to mutual agglomeration between particles at high temperatures. 2.3 The catalytic activity of SFZ The experimental conditions were the same as 1.3. The catalytic activity of SFZ catalyzed synthesis of n-butyl acetate was investigated. The results showed that the catalytic activity of SFZ8 and SFZ15 was the best, which was consistent with the fruit. 2.4 SFZ Reuse Performance The advantages of reusability are one of the important characteristics of solid super acid catalysts.
The repeatability experiment of esterification reaction using SFZ8 and SFZ15 as catalysts shows that the catalytic activity of SFZ15 from the second time is not high, and the esterification rate of SFZ8 after using 5 times is still not less than 80%, and The catalytic activity of SFZ8 is much higher than that of SFZ15 when it is used for the first time. It shows that the application of ultrasonic irradiation in the coprecipitation stage of preparing SFZ solid superacid catalyst can not only improve the catalytic activity of SFZ, but also improve the stability of use of SFZ.
This may be due to the special effect of ultrasonic cavitation, which leads to the fine and regular precipitation of particles in the process of UCOP. When impregnated with sulfuric acid, the amount of SO2-4 which interacts strongly with the sample increases, and the bonding is firmer. The super acid has a large number of acid sites, so its catalytic activity is high and its stability is good. The IR analysis of 2.5SFZ attributed the absorption peak near 1631 cm-1 to the OH deformation vibration peak of the surface metal atom adsorbing water.
The absorption peak at 997cm-11226cm-1 is the S=O bond stretching vibration absorption peak of the surface of the SFZ metal oxide combined with SO2-4. The strength and the amount of the peak reflect the amount of the surface active center of the catalyst. It can be seen that the absorption peak intensity of SFZ8 and SFZ11 at 997cm-11226cm-1 does not change significantly with the increase of calcination temperature; while the absorption peak intensity of SFZ15 and SFZ16 in this range decreases rapidly, that is, with the rise of calcination temperature. High desulfurization occurred. It is indicated that the surface of SFZ prepared by UCOP method has better bonding with SO2-4 and better thermal stability. It can be seen that after the use of SFZ15 and SFZ16, the absorption peak at 1400 cm-1 disappears substantially, which means that the catalytic activity is lowered; and after the use of SFZ8 and SFZ11, the intensity of the absorption peak at that point, with the number of uses The increase, although it is gradually weakening, but the change is slower, indicating that the USP method has more surface acid sites and better stability.
The data can also be proved. Conclusion: SFZ8 prepared by ultrasonic coprecipitation has a large specific surface area and high acid strength (H0=-16.0). The synthesis of n-butyl acetate was catalyzed by SFZ8. The esterification rate was 92.2%, and the esterification rate was still not less than 80% after 5 times.
Quantum Resonance Magnetic Analyzer:
Testing Procedures
1. When the power supply of the computer is not turned on, inspect whether the computer, the sensor, the printer and other equipment are connected well; the
probe of the tester must be plugged tightly;
2. Survey and record the basic conditions (name, sex, date of birth, etc.) of the tested person;
3. Start the computer and inspect whether the computer, the sensor the printer and other equipment run well;
4. Prompt the tested person to relax the feeling, not to speak and to keep steady breathing;
5. Require the tested person to grasp the test rod by the left or right hand;
6. Close all other application programs and open [Quantum BIO-Electric System] for testing.
7. During testing, the test person`s skin should not be touched; the hand should naturally press to grasp the test rod and not wobble.
8. After the testing is finished, the instrument should be cleaned to make it be in a good standby condition.
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