Aqua regia activated Au/C catalysts for the hydrochlorination of acetylene

Abstract

Au/C catalysts are effective materials for the gas phase hydrochlorination of acetylene to vinyl chloride monomer, and to date, the most effective catalyst preparation protocol make use of impregnation using aqua regia. In the present study, the effect of this solvent is evaluated and discussed in detail by modifying the ratio of HCl and HNO 3 and the temperature of the impregnation step. These factors are observed to affect the Au 3+ /Au 0 ratio of the final catalyst, in addition to the modification of the functional groups of the carbon used as support. The results can be rationalized by the oxidation effect of HNO 3 on both the gold nanoparticles and the functional groups on the carbon surface, as well as a nucleation effect of HCl towards gold over the carbon support. Kinetic parameters for the reduction of Au 3+ to Au 0 were also determined and these support the existence of a redox cycle between Au 3+ /Au 0 that could explain the overall catalytic activity.

Enhancement of Au/AC acetylene hydrochlorination catalyst activity and stability via nitrogen-modified activated carbon support

“…The XPS results on the elemental composition are basically consistent with the results reported in the literature [35]. XPS confirmed the presence of nitrogen species and revealed a nitrogen content of 2.9 wt.% for Au/NAC1 sample, while it is 0.23 wt.% for Au/AC1, indicating that nitrogen atoms has been successfully doped into the support.…”

Cycloisomerization of 2‐Alkynylanilines to Indoles Catalyzed by Carbon‐Supported Gold Nanoparticles and Subsequent Homocoupling to 3,3′‐Biindoles

“…[20] We were pleased to find that by this strategy, total conversion was attained, and we could even reduce the catalyst loading from 1 % to 0.5 % and the reaction time from 48 h to 16 h while retaining excellent yields (Table 1, …”

“…[11, 19,20] We appreciated the analogy with our system and we produced a range of catalysts by incipient wetness (IW) with aqua regia (HNO 3 /HCl 1:3) on active carbon following Hutchings procedure. [20] We were pleased to find that by this strategy, total conversion was attained, and we could even reduce the catalyst loading from 1 % to 0.5 % and the reaction time from 48 h to 16 h while retaining excellent yields (Table 1, …”

Synthesis of Au/C Catalysts by Ultrasonic-Assisted Technique for Vinyl Chloride Monomer Production

“…The change in catalytic activity with time is likely to be due to the change in size of gold catalyst by sintering. It was reported earlier that there is an optimum size of gold to catalyze the reaction [23,30]. Fig.…”