Preparation Of Hydrophobic Silica Gel And The Application In Oil And Gas Recovery

Petroleum inevitably has a lot of evaporation loss in the process of mining, processing, storage, transportation, sales and use. The evaporation of oil will not only cause the loss of oil, the decline in the quality, but also will seriously pollute the environment, and simultaneously have a very serious fire hazards. Therefore, it is necessary to recycle the volatile oil and gas. And the oil gas adsorption recovery technology has been a research topic which is widely concerned by home and abroad. It is the key factor for the adsorption of oil and gas recovery technology to choose a suitable adsorbent. Japanese patent mentioned a new type of oil and gas adsorbent-hydrophobic silica gel without flammable. Its thermal conductivity is lower than activated carbon, and it is difficult to break when it contacts water, etc. Hydrophobic silica gel has a good prospect of application in the field of oil and gas recovery. Based on the premise, this paper mainly focuses on the following exploration and study.1. Using sol-gel method, hydrophobic silica gel is prepared by surface modification a sodium silicate-based wet-gel slurry. This paper mainly discusses the effect of NaCl solution, silica sol pH value, aging temperature, modifier proportion, and modification time on the performance of the hydrophobic silica gel. The study finds that:the pH value of silica sol is7, and the aging temperature is60℃, and when the volume fraction of modified agents in hexane and ethanol mixture solution is50%, the wet gel is modified12h at room temperature. And the resultant material is dried in the electric oven of100℃for12h. The specific surface area of the obtained hydrophobic silica gel is613.2m2/g, and the most probable average pore size is8nm.2. Chemical bonding in the sodium silicate-based mesoporous hydrophobic silica gel is studied using FT-IR spectroscopy. After modification, the-OH peak intensities of the sample are significantly reduced. The strong absorption peak at2980cm-1corresponds to the terminal-CH3group, and those at1350cm-1and870cm-1are due to Si-C bonding. These bands, which are not present in the spectra of unmodified silica gel, are attributed to provide substantial support for surface modification of the wet-gel slurry by DB-8831. And the Si-OH of the surface is replaced by hydrophobic groups.3. The adsorption stability of hydrophobic silica gel is very good. The adsorption quantity is not reduced with the increase of number of adsorption and basically remains unchanged. The initial adsorption activity of ordinary AC and ACF is higher. At the second time, the adsorption of ordinary AC and ACF for heptane and120#aviation gasoline reduces to a great degree. From the third time, their adsorption performance remaines unchanged. After vacuum desorption, the adsorption capacity of hydrophobic silica gel for n-heptane and gasoline is greater than ordinary AC and ACF. The desorption residues of ordinary AC and ACF for n-heptane and120#aviation gasoline are large and the residues are about200-300mg/g. The residues of hydrophobic silica gel for n-heptane and120#aviation gasoline are almost0. This indicates that the obtained hydrophobic silica gel has better vacuum desorption properties and it has a long service life.4. The dynamic adsorption curve of120#aviation gasoline on the hydrophobic silica gel adsorption bed indicates:the slope of hydrophobic silica gel adsorption bed is larger and the mass transfer zone is shorter and the utilization of the bed is higher. Therefore, hydrophobic silica gel has a good prospect of application in the field of oil and gas recovery used vacuum desorption method.