Process phenol hydrogenation

Process Phenol ( hydrogenation/ nitric oxidationj i 1 Air oxidation (cobalt)/ nitric oxidation Air oxidation (boric add)/ nitric oxidation... 

By-product processing CO, H2S, methane, ammonia, H2, phenols, hydrogen cyanide, N2, benzene, xylene, etc. Electrostatic precipitator, scrubber, flaring... 

The acetoxy dienone (218) gives phenol (220). Here, an alternative primary photoreaction competes effectively with the dienone 1,5-bonding expulsion of the lOjS-acetoxy substituent and hydrogen uptake from the solvent (dioxane). In the case of the hydroxy analog (219) the two paths are balanced and products from both processes, phenol (220) and diketone (222), are isolated. In the formation of the spiro compound (222) rupture of the 1,10-bond in the dipolar intermediate (221) predominates over the normal electron transmission in aprotic solvents from the enolate moiety via the three-membered ring to the electron-deficient carbon. While in protic solvents and in 10-methyl compounds this process is inhibited by the protonation of the enolate system in the dipolar intermediate [cf. (202), (203)], proton elimination from the tertiary hydroxy group in (221) could reverse the efficiencies of the two oxygens as electron sources. 

This study shows that the optimization of process conditions could be achieved rapidly by a judicious use of statistics and parallel reactors. A two-level factorial method with two center points was used to limit the total number of experiments to ten. Using two identical high-pressure reactors in parallel further shortened the time required to conduct these experiments. For the model reaction of phenol hydrogenation over a commercially available Pd/C, it was experimentally determined that the optimal yield was 73% at 135 °C, 22.5 bar, and 615 ppm w/w NaOH... 

Lignol [Lignin phenol] A catalytic process for hydrogenating lignin to a mixture of phenol, benzene, and fuel gas. Developed by Hydrocarbon Research. See also Noguchi. 

The 17r<7 states also dominate the photoinduced processes in hydrogen-bonded chromophore-solvent clusters. The photoinduced hydrogen transfer reaction is experimentally and computationally well documented in clusters of phenol and indole with ammonia [14,16,32], There is no clear evidence for the existence of an excited-state proton transfer process in these systems [14], The same conclusion applies to bi functional chromophores solvated in finite clusters, such as 7HQ-ammonia and 7HQ-water clusters [15]. In future work, the photochemistry of larger and biologically relevant chromophores (such as tyrosine, tryptophan, or the DNA bases) should be investigated in a finite solvent environment. 

In earlier processes phenol could only be converted into Cyclohexanone in a two-step process 1) First the ring in the phenol was hydrogenated with a nickel catalyst at 140 to 160%] and 15 bar and then 2) the dehydrogenation was conducted as shown in Eq. (21.1)46. 

The production of Cyclohexanone from phenol was simplified when selective hydrogenation with Pd catalysts was made possible ([see Eq. 21.3)]. In this process, phenol is completely converted in the gas phase at 140 to 170°C and 1 to 2 bar using a supported Pd catalyst containing alkaline earth oxides (e.g., Pd-CaO/A Os). The selectivity to Cyclohexanone is greater than 95%46. 

The process based on phenol hydrogenation considered here can be described by the following overall stoichiometric equation ... 

The above kinetics is valid for small particles when the process rate is controlled by the chemical reaction at the surface. Diffusion effects should be accounted for large-size particles. Table 5.8 presents the calculation of the effectiveness factor [24] for spherical particles of 6 mm diameter and a mixture 1 3 phenol/hydrogen at 2 bar and 423 K. Other data are BET internal surface S = 40m2/g, mean pore radius 150 A, catalyst density pp = 1000kg/m3, particle void fraction = 0.3,... 

Figure 5.21 Simulation of one-reactor phenol hydrogenation process.

The case study of cyclohexanone manufacturing by phenol hydrogenation illustrates the basic principles of the conceptual development of a process flowsheet. For more complexity we consider a two-step process. Firstly, phenol is submitted to hydrogenation, in which both cyclohexanone and cyclohexanol... 

Phenol Hydrogenation. In principle, appropriate lignin deconstruction processes will provide a stream of mixed phenols. Reduction of these phenols will lead to a new source of cyclic aliphatic alcohols of potential use in the manufacture of adipic acid derivatives. Several catalytic processes for these types of reductions have appeared for phenol and should be applicable to lignin-derived mixed phenols. Phenol itself is reduced to cyclohexanol in the presence of various heterogeneous catalysts based on Pd.530-535... 

In the phenol hydrogenation process phenol is fed in the gas phase with hydrogen at 140-170°C through a catalyst bed at atmospheric pressure. The catalyst generally consists of 0.2-0.5 wt.% palladium on a zeolite carrier. The yield exceeds 95% at quantitative conversion. Figure 2.28 shows the flow diagram for the process. 

Kvaerner Process Technology Cyclohexanone/cydohexanol Phenol/hydrogen Synthesis of KA oil with high selectivity to cyclohexanone 2 1998... 

The actual process requirements of phenol, hydrogen, nitric acid, and utilities and consumables have been determined to be... 

The adipic acid process is a relatively complex process and essentially contains two plants phenol hydrogenation and KA oil oxidation. We should therefore assume at least four shift positions for each plant, say nine total. For a Northeast Asia basis, we expect that the salary cost per shift position will be lower than the typical 50,000 per year that we would assume for a U.S. Gulf Coast plant. As a first approximation this is estimated as 30,000/y. The remaining salary and overhead costs are fixed following the assumptions given in Section 6.2.4. 

These antioxidants include the hindered phenols and are considered to be most effective when the chain-carrying (propagation) radical is an -oxy radical such as alkyl peroxy, R02. Thus, in reactive processing, they would be expected to be of value in suppressing the oxidation reactions which can occur in the earlier zones of a reactive extruder. The chemistry of these systems has been studied in detail (Al-Malaika, 1989, Scott, 1993b), and it has been found in the case of hindered phenols that the effectiveness of these stabilizers is dependent on the chemistry of the oxidation product rather than the simple donor reaction of the phenol hydrogen atom to the propagating radical. 

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