Reduction of 4-nitrophenol to 4-aminophenol using Pt/HKUST-1 catalyst

The catalyst Pt/HKHUST-1 was used for synthesis 4-aminophenol (4-AP) by reducsion 4-nitrophenol (4-NP). Factors that affected to the reaction were tested: ratio 4-NP/NaBH4, temperature and time of the reaction. Changing the ratio of 4-NP/NaBH4 in the direction of increasing NaBH4, the reaction rate increases. However, it is acceptable to reduce the reaction rate when synthesizing with high concentration of reactants. The 4-AP synthesis is performed with ratio 4-NP/NaBH4 = 1/5, suitable time and temperature for this reaction is 60 minutes and 15 oC. The catalyst sample containing 2% Pt on HKUST-1 material was used to synthesize 4-AP with the yield of 65.3% (average 64.2%), the catalyst has good stability, can reused many times. The purity of 4-AP after refining was 99 %.

Reduction of 4-nitrophenol to 4-aminophenol using Pt/HKUST-1 catalyst

The catalyst Pt/HKHUST-1 was used for synthesis 4-aminophenol (4-AP) by reducsion 4-nitrophenol (4-NP). Factors that affected to the reaction were tested: ratio 4-NP/NaBH4, temperature and time of the reaction. Changing the ratio of 4-NP/NaBH4 in the direction of increasing NaBH4, the reaction rate increases. However, it is acceptable to reduce the reaction rate when synthesizing with high concentration of reactants. The 4-AP synthesis is performed with ratio 4-NP/NaBH4 = 1/5, suitable time and temperature for this reaction is 60 minutes and 15 oC. The catalyst sample containing 2% Pt on HKUST-1 material was used to synthesize 4-AP with the yield of 65.3% (average 64.2%), the catalyst has good stability, can reused many times. The purity of 4-AP after refining was 99 %.

Modification HKUST-1 as a catalyst for the reduction of 4-nitrophenol

HKUST-1 (MOF-199), a metal-organic framework material is synthesized from Cu(OH)2 and modified by Pt. The prepared catalysts were used to reduce 4-nitrophenol (4-NP) into 4-aminophenol (4-AP). Featured results of the catalysts by XRD, SEM, TEM, FTIR, BET, DTA/TGA... showed that metal modified process with reduced agent ethylene glycol had high efficiency, with modified yield up to 90 %. Under our experimental conditions, the catalysts based HKUST-1, containing Pt had high efficiency; conversion was greater than 93 % in reduced reaction of 4-NP. Thus, the catalyst sample contained 2% Pt was the most suitable for the reduction with conversion gained 99,4 % after 250s.

Recent Advances in Metal Organic Frameworks Based Surface Enhanced Raman Scattering Substrates: Synthesis and Applications

Metal-organic frameworks (MOFs) are supramolecular nanomaterials, in which metal ions or clusters are connected by organic ligands to form crystalline lattices with highly ordered periodic porous network structure. MOFs have been widely applied in various fields, such as catalyst, sample preparation, and sensing. In recent years, MOFs based surface enhanced Raman scattering (SERS) substrates have attracted much attention since MOFs can largely improve the performance of metallic SERS substrates toward target enrichment and signal enhancement. MOFs have been exploited in SERS analysis to tackle some challenges that bare metal substrates cannot achieve. Combination of MOFs and SERS improved the sensitivity of traditional SERS analysis and extended the application scope of SERS. With the increasing exploration of MOFs based SERS substrates, there is a great demand to review the advances in these researches. Herein, this review concentrated on summarizing the preparation and applications of MOFs based SERS substrates. Representative researches were discussed to better understand the property of MOFs based SERS substrates. The advantages of MOFs based SERS substrates were highlighted, as well as their limitations. In addition, the challenges, opportunities, and future trends in MOFs based SERS analysis were tentatively discussed.

Improvement in Metal Dissolution from Spent Catalyst by Adapted Acidithiobacillus ferrooxidans

The improvement in the leaching rate of Ni, V, Mo, and Al present in a spent catalyst sample was evaluated by the bacterial adaptation technique. For this purpose, leaching of the metals from the spent catalyst sample was conducted using both adapted and unadapted bacteria cultures. The evaluation was done on the basis of the variation of different leaching parameters such as pH, temperature, particle size, pulp density, and initial Fe(II) concentration. The adaptation technique was found to be fruitful as the leaching equilibrium reduced from 240 to 40hr. Further, the leaching rate of Ni and V was improved by 10%(w/w) due to bacterial adaptation. The leaching rate of Mo was lower due to combining the action of different factors like the presence of impervious elemental sulfur, refractory nature, and low solubility. The lower leaching rate of Al observed due to the refractoriness of the alumina matrix present in the spent catalyst sample. The pseudo rate order with respect to all leaching parameters was determined and found to be significant for the adaptation process.

BIFUNCTIONAL СО/SIO2-Fe-ZSM-5-Al2O3 CATALYSTS FOR SYNTHESIS OF HYDROCARBONS OF ENGINE FRACTIONS

The process of obtaining motor fractions of hydrocarbons on bifunctional Со/SiO2-Fe-ZSM-5-Al2O3, catalysts obtained by mixing has been studied. The effect of the method of introducing iron into a catalyst (in the form of reduced iron and its nitrate) at the molding stage is studied. The catalysts were tested in a continuous mode for 30 h at a gas volume velocity of 1000 h-1, a pressure of 2 MPa and a temperature of 240 ° C. It is shown that when iron is introduced in the form of a reduced powder, the temperature gradient in the catalyst bed decreases, and the selectivity for C5+ hydrocarbons increases by 6% in comparison with the catalyst sample without the addition of iron. It has been established that the introduction of iron into the catalyst in the form of a nitrate salt is a less effective method. It blocks the operation of polymerization and acid sites of bifunctional catalysts, contributes to a reduction in CO conversion and selectivity for C5+ hydrocarbons. It is shown that the introduction of iron significantly changes the group composition and molecular-mass distribution of the produced hydrocarbons - the shares of saturated hydrocarbons are increases, predominantly of a linear structure, the yield of olefins decreases. The obtained C5+ hydrocarbons mainly consist of gasoline and diesel fractions. The introduction of iron promotes an increase in the content of diesel fractions in synthesis products. Thus, with the introduction of iron in the form of a nitrate salt, the content of the diesel fraction increased by 1.2 times in comparison with the sample of a catalyst without iron.

OXIDATION OF ALCOHOLS OVER CERIUM-OXIDE CATALYST: CORRELATION BETWEEN THE ACTIVATION ENERGY OF THE REACTION AND THE CHEMICAL SHIFT δ (R13 COH)

The oxidation of thirteen alcohols over sup-ported CeO2/Al2O3 catalyst with 10 wt.% of CeO2 have been studied using a desorption mass-spec-trometry technique. A catalyst sample 4–6 mg in quartz cuvette was evacuated at 100 0C, cooled to room temperature, and then adsorption of a alco-hol was provided. After vacuumation of alcohol excess, the TPR profiles of products of alcohol oxidation were recorded at sweep rate 2 a.u.m./sec and heating rate of 15 0C/min using MX-7304A monopole mass- spectrometer. Identification of formed aldehydes and ketones was provided on the bases of their characteristic ions in obtained mass-spectra, namely, acetaldehyde (m/e = 29, 44); pro-panal (29, 58); acetone (43, 58); butanal (44, 43); methyl propanal (43, 41, 72), 2-butanon (43, 72); methoxyacetone (45, 43); cyclohexanone (55); ace-tophenone (105, 77); benzaldehyde (77, 106). It was shown that the oxidation of several alcohols pro-ceeds in a wide temperature interval from 130 to 280 0C. So, peak of formaldehyde formation from me-thanol adsorbed on CeO2/Al2O3 is observed at 280 0C whereas peaks of methyl glyoxal and water formation from adsorbed hydroxyacetone are re-corded at 135 0 C. The linear correlation between activation energy of reaction and chemical shift δ (R13COH) of studied alcohols was found as Ea= 183 –1.4δ (kJ/mol). Respectively, the maximum oxi-dation rate, for instance, for methanol (50 ppm) is observed at 280 0C, for ethanol (58 ppm) at 215 0C, for n-butanol (62 ppm) at 200 0C, for n-propanol (64 ppm) at 190 0C, for 2-butanol (69 ppm) at 160 0C, for hydroxyacetone (69 ppm) at 135 0C, and for 1-phenylethanol (70 ppm) at 130 0C. Thus, ability of alcohols to oxidation decreases with increase of their electronic density on carbon atom of alcohol group in following order: 1-phenyl ethanol ≈ hyd-roxyacetone ≈ cyclohexanol > allyl alcohol ≈ 2-bu-anol ≈ i-butanol ≈ i-propanol > methoxypropanol-2 ≈ n-propanol ≈ n-butanol ≈ benzyl alcohol ≈ ethanol >> methanol. On an example of ethanol, the scheme of alcohol oxidation on ceria that assumes the addition of atomic oxygen to C–H bond of alcoho-lic group with intermediate acetaldehyde hydrate formation is discussed.

Influence of Impurity Dissolution on Surface Properties and NH3-SCR Catalytic Activity of Rare Earth Concentrate

Impurity removal and modification of rare earth concentrate powder were conducted by roasting weak acid-weak alkali leaching to obtain the active components of denitrification catalysts. NH3 selective catalytic reduction catalyst samples were prepared by mixing and kneading with pseudo-γ-Al2O3 boehmite as carrier. The results showed that the Ce7O12 content in the active component samples increased and dispersed more evenly. The grain size of the samples was refined, the specific surface area increased, and the active sites exposed more. Ce coexists in the form of Ce3+ and Ce4+. Fe coexists in the form of Fe3+ and Fe2+, but Fe3+ is abundant. Some Ce, La, Nd, Pr, Fe, Mn, and other components formed solid melts during preparation, which increased the synergistic catalytic effect. The denitrification efficiency of the catalyst sample was 92.8% under the conditions of reaction temperature 400 °C, NO content was 600 ppm, NH3/NO ratio was 1.5, and O2 concentration was 4%.

Sol- Gel Synthesis of Hematite Nanoparticles and Photo Degradation of Cibacron Red FN-R Dye

This paper describes the synthesis of ?- Fe2O3 nanoparticles by sol-gel route using carboxylic acid(2-hydroxy benzoic acid) as gelatin media and its photo activity for degradation of cibacron red dye . Hematite samples are synthesized at different temperatures: 400, 500, 600, 700, 800 and 900 ?C at 700 ?C the ?-Fe2O3 nanoparticles are formed with particle size 71.93 nm. The nanoparticles are characterized by XRD , SEM, AFM and FTIR . The 0.046 g /l of the catalyst sample shows high photo activity at 3x10-5M dye concentration in acidic medium at pH 3.