Impregnation time

In this work, various conditions have been used for preparing catalysts to screening out a proper one mainly for CTA hydrogenation. The palladium precursor, impregnation time, calcination and reduction will be taken into account. 

Table 1 Effect of impregnation time on the catalytic iMitivity...

Preparation conditions of Pd/CNFs by wet impregnation method, such as palladium precursor, impregnation time, calcinations and reduction, are proved to have profound effect on the catalytic property. The catalyst prqjared by impregnating HzPdCLi precursor in an hour, then calcinated in air and reduced in 20%H2/Ar is believed to perform better in CTA hydropurification than the industrial Pd/C under laboratory conditions. 

During drying an outward flow of Pt can exist, leading to loss of dispersion. The resulting system will depend on many factors, including impregnation time and pH value, viscosity, concentration of the impregnating solution, and the presence of other ions or solute in the solution. 

Figure 3.30. Change of Pt front with increasing impregnation time.

Impregnation time Short Long Short Short Very long... 

A composite obtained from aerosil and an ethanol-water (2 1) mixture with a total porosity of 65% was used as the matrix to be impregnated with polystyrene solutions. The impregnation time was 7 and 24 h. 

Fig. 13.5. Effect of impregnation time on the quantity of nickel salt adsorbed and its distribution within the support particle on impregnation of alumina with aqueous Ni(N03)2. (Redrawn using data from Ref. 77.)...

According to these figures along with the models, several remarks can be made. Firstly, as the impregnating time or drying temperature increases, the mean strength decreases at first and then increases. The mean strength takes a minimum at about t = l and Tj =... 

Siau, J. F. The Effects of Specimen Length and Impregnation Time upon the Retention of Oils in Wood. Wood Science, 1972,4(3) 163-170. 

The aim of this research project is the design and synthesis of optimal monolithic reactors and its use in deep desulfurization. In order to do so, state-of-the-art HDS powder catalysts were first prepared and their activity in thiophene HDS compared to the monolithic catalysts. These monolithic catalysts were prepared from cordierite and coated first with two layers of a-AI2O3 followed by one layer of Y-AI2O3. The coated monoliths were then impregnated with NiMo solutions (optimized for the powder catalysts) and some parameters were optimized (such as impregnation time and drying procedure). Finally, monolithic catalysts with the same characteristics as powder catalysts were obtained. 

Fig. 2 Selected preparation parameters. Impregiiation, drying and calcination steps are described by the following parameters impregnation time (tj), ratio iKtween volume of solution and pore volume of support (V.A p), pH of solution, stiriit speed (n), and corresponding temperature (T), heating ramp (s) and time (t) of drying and calcination with subscription d and c, respectively.

In general, the results from the left branch of the regression tree indicate the importance of the amount of impregnating solution, impregnation time and drying speed (preparation parameters). 

The absence of chemical catalysts enables the impregnation time to be modulated. Nonconsumed resin can be recycled and safely stored if appropriate conditions are applied. 

Impregnation. Three samples of each species were used for each monomer or resin bath. The wood-to-bath volume ratio was at least 1 10. Samples were soaked in a 10% water-diluted N-vinylpyrrolidone (NVP) solution that was later replaced three times by pure NVP. The baths were darkly stained by wood tannins. Impregnation time was about 4 weeks. 

No significant volumetric change was observed on oak samples after dehydration. On the other hand, deteriorated beech samples showed a mean volumetric shrinkage of 3% in both solvents. Acetone-impregnated samples were immersed for 2 weeks in Norsodyne and Ludopal resins diluted by 15% acetone in each first bath. The solutions were then changed three times by pure resins at 2-week intervals, totaling an impregnation time of 8 weeks for this final phase. 

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