Metal loaded zeolite adsorbents for hydrogen cyanide removal

Metal （Cu, Co, or Zn） loaded ZSM-5 and Y zeolite adsorbents were prepared for the adsorption of hydrogen cyanide （HCN） toxic gas. The results showed that the HCN breakthrough capacity was enhanced significantly when zeolites were loaded with Cu. The physical and chemical properties of the adsorbents that influence the HCN adsorption capacity were analyzed. The maximal HCN breakthrough capacities were about the same for both zeolites at 2.2 mol of HCN/mol of Cu. The Cu2p XPS spectra showed that the possible species present were Cu2O and CuO. The Nls XPS data and FT-IR spectra indicated that CN- would be formed in the presence of Cu＋/Cu2＋ and oxygen gas, and the reaction product could be adsorbed onto Cu/ZSM-5 zeolite more easily than HCN.

Plasma Electron Density Measuring and Processing on the J-TEXT Tokamak

Plasma electron density is one of the most fundamental parameters in the study of tokamak plasma physics.The method of plasma electron density measuring and processing on the Joint Texas Experimental Tokamak(J-TEXT) was presented in this paper.The principle of the plasma electron density measuring by hydrogen cyanide(HCN) laser interferometer was introduced.Room temperature triglycine sulface(TGS) detector was used to obtain the beat signal of HCN,and phase difference was measured by high-speed acquisition card DAQ2010.Based on the signal characteristics,a specific HCN processing algorithm was designed to eliminate the baseline offset accurately and process overturns of HCN signals effectively.As a result,plasma electron density with high accuracy and low noise has been obtained during the J-TEXT tokamak experiment.

Potential of Fermentation in Detoxifying Toxic Cassava Root Tubers

Quantitative determination of hydrogen cyanide （HCN） content in a toxic local cassava variety ＂Rutuga＂ with an initial total HCN of 16.65%, free HCN of 9.19% and bound HCN （cyanoglycosides） of 7.46% in the fresh peeled root tubers was done to assess the effectiveness of aquatic and terrestrial （heap） fermentation in detoxifying cassava root tubers for obtaining dried product used in making flour. This was indirectly done by getting the difference in HCN content that remained after processing the root tubers using some traditional processing techniques. The findings indicated that aquatic fermentation in water from river Rwizi for 4 days only removed 1.23% of total HCN, 0.05% of free HCN and 2.68% of Cyanoglycosides （bound HCN） while terrestrial （heap） fermentation for 4 days removed 50.33% of total HCN, 20.84% of free HCN and 86.66% of Cyanoglycosides （bound HCN）. Therefore, terrestrial （heap） fermentation has a higher potential in removing total HCN, free HCN and cyanoglycosides （bound HCN） than aquatic fermentation, especially in water from river Rwizi.

Adsorption of HCN on Ni/Pt(111)Bimetallic Surfaces Investigated with Density Functional Theory Method

We applied periodic density-functional theory to investigate the adsorption of HCN on x Ni@Pt（111） bimetallic surfaces（x = 1~4）. The results have been compared with those obtained on pure Ni（111） and Pt（111） surfaces. For all bimetallic surfaces,HCN is preferentially tilted with the CN bond parallel to the surface,and adsorption energies increase with an increasing number of layer Ni atoms on the surface. The adsorption energies of HCN on all bimetallic surfaces are larger than that on the Pt（111） surface,whereas the adsorption energies of HCN on 3Ni@Pt（111） and 4Ni@Pt（111） are larger than that on the Ni（111） surface,indicating that the introduction of Ni to the Pt catalyst could increase the activity of bimetallic catalyst in the hydrogenation reaction for nitriles. Larger adsorption energy of HCN leads to a longer C–N bond length and a smaller CN vibrational frequency. The analysis of Bader charge and vibrational frequencies showed obvious weakening of the adsorbed C–N bond and an indication of sp2 hybridization of both carbon and nitrogen atoms.

Catalytic hydrolysis of gaseous HCN over Cu-Ni/γ-Al2O3 catalyst： parameters and conditions

To decompose efficiently hydrogen cyanide （HCN） in exhaust gas, γ-Al2O3-supported bimetallicbased Cu-Ni catalyst was prepared by incipient-wetness impregnation method. The effects of the calcination temperature, H2O/HCN volume ratio, reaction temperature, and the presence of CO or O2on the HCN removal efficiency on the Cu-Ni/γ-Al2O3 catalyst were investigated. To examine further the efficiency of HCN hydrolysis, degradation products were analyzed. The results indicate that the HCN removal efficiency increases and then decreases with increasing calcination temperature and H2O/HCN volume ratio. On catalyst calcined at 400℃, the efficiency reaches a maximum close to 99% at 480 min at a H2O/HCN volume ratio of 150. The HCN removal efficiency increases with increasing reaction temperature within the range of 100v-500℃ and reaches a maximum at 500℃.This trend may be attributed to the endothern＇ficity of HCN hydrolysis; increasing the temperature favors HCN hydrolysis. However, the removal efficiencies increases very few at 500℃ compared with that at 400℃. To conserve energy in industrial operations, 400℃ is deemed as the optimal reaction temperature. The presence of CO facilitates HCN hydrolysis andincreases NH3 production. 02 substan.tially increases the HCN removal efficiency and NOx production but decreases NH3 production.