The Effect of TiO2 Contained within a Titanium Silicalite (TS-1) Catalyst and on the Selective Oxidation of Ammonia

Abstract

The selective oxidation of ammonia to hydroxylamine using titanium silicalite-1 as a catalyst with an increasing content range of 1–2.5 wt% TiO2 was systematically investigated in a batch reactor. The hydroxylamine yielded 33, 43, 52 and 62% at reaction temperatures of 50, 60, 70 and 80°C, respectively, for 8 min using a TS-1a catalyst, which contained 2.5% TiO2. The molar ratio of 15 NH3/H2O2 was kept during these reactions. Experiments were also conducted with different amounts of NH3/H2O2 in molar ratios, which were between 7 and 60 to investigate the effect of NH3/H2O2 molar ratio on the reactions. Reactions with higher ratios of NH3/H2O2 were seen to have a higher yield at the end of the reaction performance time.

Effect of triethylamine treatment of titanium silicalite-1 on cyclohexanone ammoximation in a continuous system

“…Fig. 5 shows the 29 Si MAS NMR spectra of the TS-1 samples before and after TEA treatment. A dominant uptake centered at -113 ± 1 ppm and a distinguishable shoulder at -103 ± 1 ppm can be identified, which are assigned to the Q 4 groups in Si(SiO) 4 and Q 3 groups of silicon-bearing OH groups, i.e., Si(OH)(SiO) 3 [60,61].…”

“…UV-Visible diffuse reflectance spectra (UVVis) were obtained on a Hitachi U-3010 spectrometer using BaSO 4 as the standard reference material. The 29 Si MAS NMR measurements were performed on a Varian InfinityPlus (300 MHz) nuclear magnetic resonance spectrometer operating at ambient temperature, and the chemical shifts were referenced to tetramethylsilane. The amounts of the deposited materials after reaction were determined by a Shimadzu TGA-50 thermogravimetric analyzer.…”

“…In this mechanism, hydroxylamine is formed via the oxidation of ammonia by hydrogen peroxide on the framework Ti atoms of TS-1, and then the hydroxylamine reacts with cyclohexanone to give cyclohexanone oxime. This process results in high selectivity and yield of cyclohexanone oxime, and has been widely investigated [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30]. However, the catalyst lifetime of TS-1 in the cyclohexanone ammoximation limits its application in industry.…”

An Integrated Process for the Synthesis of Solid Hydroxylamine Salt with Ammonia and Hydrogen Peroxide as Raw Materials

“…Mantegazza et al , proposed a direct catalytic process for the production of hydroxylamine, using ammonia (NH 3 ) and hydrogen peroxide (H 2 O 2 ) as raw materials (reaction ). It has received considerable attention for its potential economic advantage and eco-efficiency. − Nevertheless, a large excess of ammonia is required, and the molar ratio of NH 3 /H 2 O 2 is usually above 10, preferably from 30 to 50. The yield of hydroxylamine (<7.8%) is much lower referred to NH 3 . , Hence, there is a growing interest in synthesizing hydroxylamine efficiently from NH 3 and H 2 O 2 . …”