In this paper, a waste fluid catalytic
cracking (FCC) catalyst
is used as a carrier to prepare a supported non-noble metal nickel
catalyst (Ni/wFCC), which is applied to the selective hydrogenation
of citral to citronellal. X-ray powder diffraction, Fourier transform
infrared spectroscopy, and scanning electron microscopy were used
to analyze the structural characteristics of the Ni-loaded sample.
The catalyst after loading Ni still maintained a good zeolite structure,
and the surface impurities were reduced. The effect of reaction conditions
on the Ni/wFCC-catalyzed hydrogenation of citral to citronellal was
investigated, and the optimal reaction conditions were obtained as
follows: a Ni loading of 20 wt %, a catalyst amount of 5.6%, a hydrogenation
temperature of 180 °C, a hydrogenation time of 90 min, and a
hydrogenation pressure of 3.0 MPa. Under these conditions, the conversion
of citral and selectivity of citronellal were 98.5 and 86.6%, respectively,
indicating that the Ni/wFCC catalyst had strong catalytic activity
and selectivity. This research provided new ideas for the recycling
of waste FCC catalysts and industrial synthesis of citronellal.
To overcome the relatively low resolution in the separation and quantitative analysis of mixtures of nitrite and nitrate, a reversed-phase ion-pair liquid chromatographic method is developed with advantages of high accuracy, good selectivity, high efficiency, and low cost. By employing cetyltrimethylammonium bromide (CTAB) as the ion-pair reagent, this method can work excellently in situations where one component in the mixture is highly in excess (e.g., molar ratio of n( NO 2 − ):n (NO 3 − ) ranging from 1:99 to 95:5). The operation parameters were optimized on a Shim-pack VP-ODS(150 L × 4.6) analytical column using a methanol/water ratio of 50:50 (v/v) mobile phase containing 7.0 mmol/L CTAB and 3.1 mmol/L potassium dihydrogen phosphate (KH 2 PO 4 ).The column works at a temperature of 35 C with a flow rate of 1.5 mL/min. Such a protocol can be applied to monitor the formation of trace nitrous acid during the oxidative decomposition of nitric acid.
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