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Study On The Electrocatalysis Of Modified Electrode Applied In The Synthesis Of L-Cysteine

Posted on:2000-08-31Degree:DoctorType:Dissertation
Country:ChinaCandidate:M X LiFull Text:PDF
GTID:1101360185474185Subject:Industrial Catalysis
Abstract/Summary:PDF Full Text Request
The electrode applied in the electrosynthesis of L-cysteine from L-cystine was modified to resolve the problem of low activity and low current efficiency faced in this process due to the material of electrode.With Pb as the base electrode, first of all, five kinds of metals such as Ni, Sn, Cu, Bi and Zn were applied to modify the base electrode respectively and the elements Ni, Sn, Zn with better performance were selected. Then the binary alloys of these three kinds of metal were studied, the electrode modified with Ni-Sn alloy considered to be the best.Then the modification conditions of (Ni-Sn)/Pb electrode were discussed, the best conditions were considered as: modified temperature 80℃, pH2.75, current 0.30A, F7Sn2+ mole ratio 7, NiCl2 ·6H2O/SnCl2 ·2H2O mass ratio 10: 2. The performance of electrode modified in these conditions worked the best. The activity of electrode after modification enhanced greatly and the potential of cathode lowered obviously, the conversion in 30 minutes increased from 51.04% of base electrode enhanced to 81.78% of modified electrode, the current efficiency of reaction increased from 77.44% of base electrode to 80.81% of modified electrode.With the best modified electrode, the electrolysis technology of reaction were discussed. Finally, the current efficiency of reaction reached 100% when reaction temperature was 40℃.. electrolysis potential was 3.5V, hydrochloric acid/cystine mole ratio was 0.4, 0.15mol/L relatively(saturation solution of cystine), carbamide content was 1%, nitrogen used to stir the solution of reaction, and the flux of it was 25ml/min.It was discovered by the SEM-EDX of electrode that modified conditions had much effect on the surface state and element composition of electrode. It was discovered by XRD that the Ni3Sn2 crystal phase was formed on the modified electrode, probably the active center of reaction, the crystal phases formed in the modified electrode were different with various modified condition. It was discovered by XPS that, the electron binding energy of element after modification...
Keywords/Search Tags:electrocatalysis, L-Cysteine, Synthesis
PDF Full Text Request
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