Hydrofinishing

It can be seen in Table 6.8 that these changes are sufficient to improve the behavior of the oils relative to those from clay treating. In the Indiana oxidation test, hydrofinishing reduced sludge (insolubles), viscosity and acid number 

Inspections on Hydrofinished and Clay-Treated Base Stocks from Western Canadian Crude 

Finishing Process Feed Clay- treating Hyd ro-finishing Feed Clay- treating Hydro- finishing 

Source J. B. Gilbert, R. Kartzmark, and L. W. Sproule, Hydrogen Processing of Lube Stocks, Journal of the Institute of Petroleum 53(526) 317-327 (1967). With permission. 

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Used oil disposal trends include waste minimisation such as by reclaiming used fluid on site, as well as recycling of mineral oil lubricants instead of disposing by incineration. The recycling effort involves a system where spent mineral oils are collected then shipped to specialty refineries where the materials are distilled, hydrofinished, and re-refined into fresh base stocks. These re-refined materials are virtually identical to virgin feedstocks. 

Hydrofinishing The final stage in a number of petroleum hydrorefining processes, commonly used in the manufacture of lubricating oil. 

Octgain A hydrofinishing process which reduces the sulfur and olefin content of gasoline without reducing its octane number. A zeolite catalyst is used. Developed by Mobil in 1994. Chem. Eng. (N.Y.), 1994,101(7), 25. 

Hydroelectric turbines, virtual two-way SMA devices in, 22 349-350 Hydroentanglement, 17 507-508 Hydrofinishing, 15 216 Hydroflumethiazide, molecular formula and structure, 5 162t Hydrofluoric acid (HF), 4 579t. See also Hydrogen fluoride North American capacity of, 14 15t production of, 14 15 silicon solubility in, 22 491-492 in sodium fluoride manufacture, 22 825 solubility of boron halides in, 4 140t solubility of metal fluoroborates in, 4 152t... 

The second approach, high severity followed by a finishing step, is more common, and several examples of this have been reported (14,109,114-116, 138-140). The major concern in this approach is that high severity with present commercial catalysts produces color fluorescence in the low-sulfur product, and hydrofinishing is necessary to restore quality. An example of exploratory studies to identify the optimal conditions in a two-stage process using conventional catalysts is shown in Table XX (114). The table shows... 

Hydrofinish the FCC gasoline. Processes exist to tackle this problem (See Chapter 4 of this volume) but always result in octane barrel losses and also require the erection of new units... 

Monitoring the Performance of Ni-Mo-Alumina Catalyst in Lube Hydrofinishing Through Catalyst Characterization A. V, Ramaswamy and L D, Sharma... 

One of the objectives of this work was to investigate whether TPR could be used to monitor changes in the reduction properties of the hydrofinishing catalyst and hence its performance- Fig, 2 shows TPR profiles of the fresh and the RGD samples, as a function of temperature, allowing programming of the temperature upto 950°C Apparently, the procedure led to complete reduction of each catalyst. The tpr profiles can be divided into two regions, a low temperature peak around 430°c for the fresh (Fig. 2 a) sample followed by a broad band at higher temperature centered around B30°C with a shoulder In between (around 62S C). 

Production of base oils by this route is sometimes described as lubricant oil hydrocracking because it is really a variant of the common refinery process of hydrocracking to make light fuel products from vacuum distillate feedstocks. It is not a complete process for making base oils. Distillation, de-waxing and usually also hydrofinishing steps are needed, just as in a conventional lube plant. 

A severe hydrotreating plant will have a flow scheme similar to the hydrofinishing unit shown in Fig. 1.11. Hydrocracking is a highly exothermic reaction, so cold hydrogen must be injected at several points in the catalyst bed to moderate the temperature rise. Operating conditions are severe, with pressures of 100-180 bar and reaction temperatures of 350 20°C. 

Further finishing treatment of the separated base oil may be required but the initial process has been developed to give improved separation. Low-severity acid/clay treatment, clay treatment alone or hydrofinishing may be required. 

Metals Metals should not be present in re-refined base oils either as wear metals, or from previous use of metal lubricant additives, or from the clay treatment or hydrofinishing catalyst fines. Metals are measured either by determining the total sulphated ash content or as individual metals by ICP analysis. 

The test run used commercially-produced zeolite catalyst, and the unit was a modified, commercial wax hydrofinisher. Charge stock was an LPG mixture of propane/propene/butanes/butenes (62% olefins) from an FCC unit. The test run lasted 70 days and product yields and selectivities were the same as in our smaller pilot plants. 

Catalytic dewaxing can also be used to produce high viscosity index (VI) lube oils, as in the Mobil s Lube Dewaxing (MLDW) process. This process uses a two-reactor system, where a ZSM-5 based catalyst is placed in the first reactor, and the product stream is then sent without intermediate separation to the second reactor containing a hydrofinishing catalyst to meet the desired final product specifications [167]. 

Formerly the final step in the refining process was treatment with adsorbent clay and filtration. This had the double function of improving the color of the oil and removing the last traces of undesirable substances such as heterocyclic compounds, the residues of solvents, etc. Clay treatment is now largely replaced by hydrofinishing, which is light hydrogenation at moderate temperatures over a suitable catalyst. 

Solvent extraction is successful as a refining procedure only with stocks of paraffinic character. Raw stocks which have too much naphthenic character do not respond to solvent extraction. For some purposes the properties of naphthenic oils are desirable and there are procedures used specifically to obtain these special stocks from naphthenic crudes. Figure 16-2 is a schematic diagram of the refining of naphthenic oils. The final step in the modern process is hydrofinishing the older process used a sulfuric acid treatment instead to reduce the content of aromatic compounds. 

Sulfur Sulfur is present in all lube plant feedstocks fractionated from crude oil and its content may be up to several percentage points. Solvent refining removes some but not all, therefore such stocks with no further treatment can contain up to several mass percent of sulfur. Hydrofinishing of solvent refined stocks can reduce this level substantially. Base stocks from conversion processes will have sulfur levels in the low parts per million (ppm) range since sulfur is relatively easily removed in severe hydroprocessing. 

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