Fabrication of CuO-doped catalytic material containing zeolite synthesized from red mud and rice husk ash for CO oxidation

Abstract

In this study a series of the CuO-doped materials containing zeolite with varying CuO contents were synthesized from red mud (RM) and rice husk ash (RHA). The rice husk ash/ red mud with the molar ratio of SiO 2 /Al 2 O 3 , Na 2 O/SiO 2 and H 2 O/Na 2 O being 1.8, 2.5 and 60, respectively, were maintained during the synthetic process of materials. The characteristic structure samples were analyzed by x-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscope (TEM), Brunauer-Emmett-Teller (BET) surface area and H 2 temperature program reduction (H 2 -TPR). The catalytic activity of samples was evaluated in CO oxidation reaction in a microflow reactor at temperature range 200 °C-350 °C. The obtained results showed that all synthetic samples there exist the A-type zeolites with the average crystal size of 15-20 nm, the specific surface area of 21.3 − 54.3 m 2 g −1 , and pore volume of 0.073 − 0.130 cm 3 g −1 . The material synthesized from RM and RHA with the zeolite structure (ZRM, undoped CuO) could also oxidize CO completely at 350 °C, and its activity was increase significantly when doped with CuO. CuO-doped materials with the zeolite structure exhibited excellent catalytic activity in CO oxidation. The ZRM sample loading 5 wt% CuO with particle nanosize about 10-30 nm was the best one for CO oxidation with complete conversion temperature at 275 °C.

CuO-Doped Catalyst Synthesized from Red Mud and Rice Husk Ash Using Urea-Nitrate Combustion Technique for <i>p</i>-Xylene Deep Oxidation

“…The obtained suspension was dried and calcined as detailed in our previous work. 20) The sample was stored overnight at room temperature before dried in air at 80, 100 and 120°C within 2 h at each temperature, then followed by the combustion process in the air at 600°C for 4 h. CuO-doped catalytic materials synthesized by ureanitrate combustion method were denoted as 5Cu(xU)/ZRM, where x represents the molar ratios of urea/nitrate, x = 1, 2, and 3, respectively.…”

“…Characteristic of reduction was investigated by H 2 -TPR method using a Gas Chromatograph GOWMAC 69-350 with a thermal conductivity detector (TCD) as described in our previous work. 20)…”

“…It could be seen that the intensity of peaks of the samples synthesized via the ureanitrate combustion method (5Cu(1U)/ZRM, 5Cu(2U)/ZRM, and 5Cu(3U)/ZRM) was higher than that of 5Cu/ZRM sample prepared without urea. 20) From XRD results, at the highest peak with 2ª = 36.1°, the average size of crystals of oxide composite in the samples was determined according to Scherrer's equation. The average crystallite sizes of oxide composite in 5Cu(1U)/ZRM, 5Cu(2U)/ZRM, and 5Cu(3U)/ ZRM catalysts were 20.0, 17.3, and 18.5 nm, respectively (listed in Table 1).…”

“…These sizes are smaller than that of 5Cu/ ZRM catalyst prepared without urea (21.3 nm). 20) Among three catalysts prepared by the urea-nitrate combustion method, the 5Cu(2U)/ZRM sample has the smallest average crystallite size. On the other hand, the appearance of diffraction peaks on XRD pattern of 5Cu(2U)/ZRM being more clearly is also observed, especially 2ª = 49.1°and 49.9°characterized for Fe 2 O 3 and CuO respectively.…”

“…So, the alkalinity is unnecessary to be neutralized and the cost of this synthesis procedure will be cheaper than ever. In our previous work, 20) catalytic nanomaterial with a part of zeolite structure (ZRM) having high activity in CO oxidation was synthesized from RM and RHA. The modification of ZRM with CuO increased active sites on the material surface, hence the catalytic activity was significantly improved.…”