Tertiary Butyl Ether Research Articles

Parameters Optimization of MTBE Reactive Distillation Process with Response Surface Methodology

Because of many variables and strong coupling effects between the reaction and distillation processes, the parameters optimization of reactive distillation (RD) process is usually a challenge work. In this study, response surface methodology (RSM) was used to design the numerical experiments and analyze process parameters of the methyl tertiary butyl ether (MTBE) reactive distillation column. Firstly, Packett-Burman design was employed to screen the significant process parameters affecting the conversion of isobutene from 10 variables. Then, a Steepest Ascent method and Box-Behnken design were applied to determine the optimum key process parameters, with maximizing the conversion of isobutene as an objective. The optimum and actual conversion of isobutene were 100 % and 97.54 % which is higher than a conversion of 91.95 % in the literature, under optimum conditions in MTBE reactive distillation process.

Evaluation of offspring sex ratio, sex hormones and antioxidant enzymes following exposure to methyl tertiary butyl ether in adult male Sprague-Dawley rats.

Methyl tertiary butyl ether (MTBE) is an oxygenated fuel additive which has been used widely in many parts of the world. This experiment was performed to determine the effect of MTBE on offspring sex ratio, sex hormones and antioxidant enzymes. A total of 20 adult Sprague-Dawley male rats were divided into four groups and received 0, 400, 800 and 1600 mg/kg/day MTBE by gavages for 30 consecutive days. At the end of the experiment, blood samples were taken for determination of sex hormones and antioxidant enzymes. Then, male rats were mated with healthy unexposed female rats and sex of offspring was determined after birth. Sex ratio was 0.48, 0.50, 0.43 and 0.50 in 0, 400, 800 and 1600 mg/kg/day MTBE groups, respectively (P = 0.91). There was significant decreasing trend for luteinizing hormone (LH) and testosterone in experimental groups (rs = -0.50, P = 0.030 and rs = -0.67, P = 0.002, respectively). No changes were observed for superoxide dismutase. However, decrease in glutathione peroxidase (GPX) was observed in all treatment groups compared with control which was significant in 400 mg/kg/day MTBE group (P = 0.016). The present study showed that paternal exposure to oral MTBE has no effect on offspring sex ratio; while, MTBE exposure could exert dose-dependent changes in serum testosterone and LH in treatment groups. The results of the present study, need to be clarified in the future studies.

Expermental study on common bletilla tube plasm with methyl tertiary butyl ether in dissolving cholesterol calculus

Objective To observe the common bletilla tube plasm (CBTP) function of protection for mucous membrane of gallbladder when pouring methyl tertiary butyl ether(MTBE) into gall bladder to dissolve cholesterol calculus. Methods Twenty-four Rabits were divied into A, B, C, D 4groups, every group has six Rabits, observe the CBTP function of protection for mucous membrane of gallbladder after pouring MTBE into gallbladder to dissolve cholesterol calculus. Results CBTP has not obviously influence for the effect of MTBE dissolving gallstone( B group 92.54% ,C group91.11%, D group 91.28% ,P > 0.05 ). CBTP has protection for mucous membrane of gallbladder after pouring MTBE into gall bladder to dissolve cholesterol calculus. CBTP can protect gall bladder and obviously relieve adverse reaction of MT- BE. Conclusion CBTP obviously relieve adverse reaction of MTBE, provide support for the perfusion litholytic. Key words: Bletilla; Methyl tertiary butyl ether; Cholesterol calculus; Mucous membrane of gallbladder

Application of Membrane Residue Curve Maps to Batch and Continuous Processes

Membrane residue curve maps (M-RCMs) [Peters et al. Ind. Eng. Chem. Res. 2006. 45, 9080] plot the change, over time, of the retentate composition in a batch still. In this paper, the relevance of M-RCMs to both batch and continuous processes is investigated. A constant relative permeability model is used for demonstration purposes, and the theory is then extended to a real system of methanol/butene/methyl tertiary butyl ether (MTBE). It has been shown that the differential material balances over a continuously operated membrane unit are mathematically equivalent to those which describe the M-RCM. The time variable in the batch setup is analogous to the spatial variable in continuous units. The retentate composition in a nonreflux continuous unit, for example, will follow the residue curve that passes through the initial feed composition. The M-RCM, in conjunction with the necessary flux equations, allows a designer to determine permeation area (or time) required in a continuous (or batch) process. Membrane columns operating at total and infinite reflux are discussed. A novel approach in synthesizing and designing hybrid distillation−membrane processes emerges: using the M-RCM in conjunction with column profile maps (CPMs) allows one to graphically interpret hybrids in an efficient manner. The method generates the attainable region (AR) for a chosen configuration and informs the designer of parameters like membrane area and number of distillation stages required.

HZSM5-filled cellulose acetate membranes for pervaporation separation of methanol/MTBE mixtures

HZSM5-filled cellulose acetate (CA) membranes were prepared by incorporating HZSM5 into CA for pervaporation separation of methanol/methyl tertiary butyl ether (MTBE) mixtures. The structural morphology, thermal and mechanical stability, and crystallinity characteristics of these filled membranes were investigated. The effects of HZSM5 content on the sorption, diffusion and pervaporation performance were evaluated. The swelling degree of the HZSM5-filled CA membranes decreased compared with that of CA control membrane. With the increase of HZSM5 content, the permeation flux increased continuously, but the separation factor first increased and then decreased. The CA membrane containing 0.2 wt% HZSM5 showed the highest separation factor of 346 with a permeation flux of 226 g/(m 2 h) for 20 wt% methanol in feed at 303 K. The diffusion coefficients of methanol and MTBE for the HZSM5-filled CA membranes were also estimated. The results showed that the membranes were highly methanol selective. Effects of operating conditions on the pervaporation performance have been systematically assessed. It was found that the permeation flux increased while the separation factor decreased with increasing the amount of methanol in the feed. When increasing temperature from 298 K to 323 K, the permeation flux increased significantly while separation factor decreased only slightly. With the increase of feed flow rate, permeation flux first increased and then decreased while separation factor first decreased and then increased.

Derivation and Properties of Membrane Residue Curve Maps

Residue curve maps have been developed for membrane permeation systems. A “thought experiment” was conducted whereby a fluid mixture was allowed to permeate through a diffusion membrane in a batch still. The differential equations which describe any residue curve are derived from mass balances, implying that membrane residue curve maps (M-RCM's) can be used for any type of membrane, provided the appropriate permeation (flux) model is used. In this paper, a simple constant relative permeability model is used for demonstration purposes, and as an example, an M-RCM is plotted for methanol/butene/methyl tertiary butyl ether (MTBE) using the appropriate flux data. The curves in an M-RCM trace the change in composition of the residual retentate in the batch still. At any time during batch permeation, the permeate composition is related to that of the retentate at that particular time, thus allowing a membrane separation vector to be defined as the vector difference between the two compositions.

MTBE in Southern California water

Motorized recreational watercraft were the predominant mode of contamination in reservoirs.Methyl tertiary butyl ether (MTBE) is a common fuel oxygenate used in motor vehicle fuels to control emissions and boost octane. It is more water‐soluble than other fuel constituents and does not adsorb well to substrates such as soil. It can contaminate groundwater supplies through leaking underground fuel storage tanks and pipelines, and through spills, urban storm runoff, and precipitation. It can also contaminate open water reservoirs through exhaust from motorized watercraft. The Metropolitan Water District of Southern California surveyed six reservoirs that supply drinking water in Southern California. Recreation on these reservoirs ranged from none at all to high activity with personal watercraft. It was found that motorized watercraft can contribute a significant amount of MTBE to the water supply.

Occurrence of MTBE in drinking water sources

A recent survey investigates the prevalence of MTBE in drinking water supplies and evaluates the efficacy of treatment for MTBE removal.Methyl tertiary butyl ether (MTBE) is of concern to the drinking water supply profession because of its strong taste and odor effects, potential risk to human health, tendency to migrate rapidly in groundwater, and resistance to conventional water treatment processes. An occurrence survey was performed from 1997 to 1998 to assess the prevalence of MTBE in surface and subsurface drinking water supplies. The survey examined 342 wells in 17 states, and MTBE was detected at least once in 30 wells (~8.8 percent). All samples were below the US Environmental Protection Agency's taste and odor advisory level of 20 μg/L. In addition, 92 surface water sites in 12 states were evaluated, and MTBE was detected at least once at eight sites (~8.7 percent). The highest concentration (25.1 μg/L) was detected downstream from a known gasoline release. Aeration removed up to 76 percent of low concentrations of MTBE, but activated carbon adsorption was relatively ineffective.

Selective isotopic oxygen incorporation into C5 and C6 ethers via solid acid-catalyzed reaction of methanol and ethanol with isobutanol

Reaction of CH318OH with16O-containing isobutanol (2-methylpropan-1-ol) over strong acid Nafion-H and Amberlyst-H 35 resin catalysts gave the two distinctly labelled C5 ethers 1-methoxy(16O)-2-methylpropane (also designated as methyl isobutyl ether,16O-MIBE) and 2-methoxy(18O)-2-methylpropane (also designated as methyl tertiary-butyl ether,18O-MTBE). Reaction of CH3CH218OH with isobutanol gave the analogously labelled C6 ethers,16O-EIBE and18O-ETBE. These results show that the isobutyl and tertiary-butyl ethers are formed from the alcohols by distinctly different mechanistic pathways, i.e. the former are produced bysurface-catalyzed SN2 reactions that follow Langmuir-Hinshelwood kinetics involving competitive adsorption while the latter arise via carbenium or olefinic intermediates. There is no pathway for isomerization of the two ethers, MIBE and MTBE, under the reaction conditions employed.

Catalysis by hydrogen halides in the gas phase. IX. Tertiary butyl ether and hydrogen bromide

The hydrogen bromide catalysed decomposition of t-butyl ethyl ether takes place at 263-337�. Two major reactions occur, one producing isobutene by kinetics first order in each reactant, and the other isobutane by kinetics first order in the ether and zero order in hydrogen bromide. The latter is extensively inhibited by cyclohexene and is a radical chain reaction; the former is not inhibited and is presumably molecular, and on this basis its properties form a smooth sequence with those of other similar hydrogen halide catalysed decompositions.