In order to understand the distribution of the surface acidity and the strength of the acid sites, a systematic study of NH 3 -TPD measurements was performed. The NH 3 -TPD profiles of H-ZSM-5 samples are shown in Figure 3. The results of ammonia TPD-titration that contain the amount of desorbed ammonia and acidity content of the prepared catalysts are summarized in Table 3. As shown in Figure 3, There are three desorption peaks in TPD profiles of catalysts with maxima in the range of 70–240, 240–430 and 430– 800°C, which can be ascribed to the NH 3 desorbed from acid sites with low, medium and high strengths, respectively. The results showed that the total acidity of the catalysts decreased with increases in the TPABr molar ratio. Many researchers have reported that strong acid sites are responsible for the formation of hydrocarbons and acid sites of weak or intermediate strength are responsible for the selective formation of DME [22, 27]. Among the prepared catalysts, Z-0Br had the highest number of weak acid sites, followed by Z-5Br and Z-10Br. Therefore, it was expected that the Z-0Br has the highest methanol conversion and DME selectivity;but Z-5Br and Z-10Br havesimilar performance toZ-0Br.
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Nanostructured CuZnFe catalysts were synthesized by coprecipitation method and successfully catalyzed in MSR reaction. The case of 30CF revealed lower methanol conversion than 30CA. Based on the Fe optimization, increase in this loading to 20 wt % resulted in higher methanol conversion and lower CO selectivity, simultaneously. Afterwards, further Cu loading from 40 to 45 wt % improved methanol conversion while with more loading a slight decrease was observed. The XRD patterns showed a nanocrystalized structure and also based on
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atoms, ions and molecules for the initiation and propagation of chemical reactions . High reaction rate and fast attainment of steady state in the plasma processes allows rapid start-up and shutdown of the plasma process, providing highly flexibility to be integrated into portable hydrogen production systems [11, 12]. Different non-thermal plasma systems have been developed for methanol conversion into hydrogen to maximize hydrogen production and energy efficiency of the plasma process, such as microhollow cathode discharge (MHCD) , microwave discharge [5-8], and dielectric barrier discharge (DBD) . However, the relatively low power level of these plasma systems makes it difficult to achieve high, efficient conversion of methanol at a high gas flow rate, restricting the potential scale-up of this process . For instance, Futamura et al. reported a methanol conversion of only 8-26% can be obtained at a feed N 2 flow rate of 100 ml/min
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It is obvious that Na-doped can perform the best to promote the activity, as that the methanol conversion in- creased from 74% to 96% of 0.1 Na/0.4 ZnAl. The activity data of Na-doped 0.4 ZnAl catalysts is consistent with the results in Figure 3, implying that the more clearly the hydroxyl group on the surface and more weaken of C-H bonds of catalysts, the higher of reforming activity. The weaken effect of C-H bond resulted in the easier dehydrogenation of methanol to form formaldehyde, which was the key intermediate of methanol reforming reacting with hydroxyl group to form the desired CO 2 and H 2 .
Fig. 6 describes the reaction temperature effect on the methanol conversion over Fe-MoI, Fe- MoII, and Fe-MoIII catalysts. The main methanol oxidation products are DMM, formaldehyde, formic acid, methyl formate, and carbon oxides (CO and CO 2 ) [39,40]. However, for the Fe-Mo catalyst, main products were DMM and formaldehyde. The temperature affects the products distribution significantly. The methanol conversion enhanced by increasing temperature from 503 to 563 K. All catalysts are similar in the variance tendency of the methanol conversion with the temperature. Nevertheless, Fe-MoII and Fe-MoIII give a better methanol conversion than Fe-MoI. Porous structures with higher surface areas of Fe-MoII and Fe-MoIII catalysts lead to surface acidity with enhanced quantity and suitable strengths, which can promote the condensation reaction and hence give a positive effect on the methanol oxidation to produce DMM.
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Zhongmin Liu (Chinese Academy of Sciences, China) presented ‘Recent Progress on Fundamental Researches of MTO Reaction’. The hydrocarbon pool mechanism, in which organic species confi ned in the zeolite cage or at the intersection of channels act as co-catalysts, has been regarded as a rational explanation for formation of C–C bonds in methanol conversion (8). Methylbenzenium cations and methylcyclopentenyl cations have been speculated to be the most important active intermediates involved in the ‘hydrocarbon pool’ mechanism. Although a reaction network was proposed, there still remain many scientifi c challenges, such as how the fi rst C–C bond forms, what happens in the induction period, what are the exact relations among different reaction routes, how coke forms, and how to control the coking reaction in the reaction network.
Nickel oxide nano with particle size of 10.0 to 15.0 nm using zeolite as a template were successfully prepared and loaded (NiO 10 wt.%) on functionalized carbon nanofibers (CNFs). The as-prepared material NiO-CNFs was characterized and tested as an electrocatalyst and a catalyst for the methanol conversion. Electrocatalytic results showed high stability which was evinced by repetitive cycles as a result of catalyst surface activation. Gas phase catalytic tests were carried out at 290 o C over NiO-CNFs catalyst in fresh, reduced, and oxidized forms. The results showed
It is found that the greater contents of methanol in feedstock improve the formation of high carbon hydrocarbons in the MTP reaction. As it was previously discussed, in superior methanol contents in feedstock, the concentration of methanol molecules on the MFI zeolite nanosheets is notably intensified which provides the more intermediates of carbenium ions to generate the heavier hydrocarbons [32, 33, 89]. While, at the same reaction temperature and WHSV increasing water contents in feedstock intensely accelerates the production of light hydrocarbons particularly ethylene (Fig. 9c) and decreases methanol conversion, with regard to Fig. 9a. This issue probably can be attributed to the reduced amount of methanol adsorption on active acidic sites of the MFI zeolite nanosheets caused by competitive adsorption of water. The conversion of methanol is dramatically repressed at extremely low methanol/water ratio (2 mol.%). As evidenced by Fig. 9(a-b), not only the methanol conversion but also the propylene selectivity is maximized in the methanol molar percent near 30%. It is resulted that a moderate concentration of methanol molecules is needed for maximizing the methanol conversion and propylene selectivity.
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Direct conversion of methane to more valuable chemicals without involving synthesis gas has long been considered good in catalysis studies. Methane can be converted to higher hydrocarbons via the oxidative coupling of methane (OCM) (Anderson et al., 1985; Bi et al., 1988; Burch and Maitra, 1993; Burch et al., 1991; Chalker et al., 1991; Conway et al., 1991; Conway et al., 1991; Ernst and Weitkamp ,1989; Korf, et al., 1992; Krylov, 1993; Maitra, 1993; Mleczko and Baerns, 1995). It can also be partially oxidized to methanol (Rytz and Baiker, 1991; Casey et al., 1994; Arutyunov et al., 1996; Lu, 1996; Liu, 1996; Lee and Foster, 1996; Raja and Ratnasamy, 1997; Lange, 2001; Otsuka and Wang, 2001). In addition, it has been demonstrated that formaldehyde could be obtained by partial oxidation of methane using molecular oxygen as oxidant (De Lucas et al., 1998). Furthermore, the direct catalytic conversion of methane into higher aromatic hydrocarbons has been extensively studied by many researchers (Wechuysen et al., 1998; Szöke and Solymosi, 1996; Shu and Ichikawa, 2001; Xiong et al., 2001a and 2001b, Choudary et al., 1997; Meriaudeau et al., 2000; Pierella et al., 1997; Liu et al., 1999, Liu et al., 2000; Xu and Lin, 1999). In particular, the single step conversion of methane into higher hydrocarbon in the range of gasoline (C 5 + ) has been reported by some
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The methanol produced in the present work biodiesel sesame oil base - catalyzed transesterification reaction. Effect of different reaction parameters, such as examining the molar ratio methanol / oil and the catalyst concentration and the optimal parameters have been found. Transesterified kinetics were examined and proposed a pseudo -first-order kinetic equation. Experimental data were fitted to the model.
In the present study, DDS derived CaO was employed as a cost effective heterogeneous catalyst for methyl esters production from CIO-WCO via transesterification process. Utilizing low-cost WCO as feedstock makes biodiesel production more economical and also prevents illegal landfilling thereby creating a safe environment. Also, the mixing of WCO with non-edible oil like CIO will act as a potential feedstock owing to the limited prevalence of CIO throughout the year. Blending of CIO with WCO at different proportions was evaluated to lower the acid value and the opted CIO-WCO (1:1 volu- metric) mixture showed a moderate acid value of 33.4 mg of KOH g − 1 oil. Further, to diminish the acid value of CIO-WCO mixture, the esterification reaction was executed using sulphuric acid as homogeneous catalyst and the acid value was further decreased to 5.6 mg of KOH g − 1 of oil. In transesterification process, the effect of transesterification time, volumetric ratio of methanol to esterified CIO-WCO and calcined DDS concentration on biodiesel conversion was investigated using CCD of
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The reactor includes a stainless steel 316vessel (3.7Lcapacity), pressure gauge and a heating jacket provided with mechanical stirrer. The temperature and pressure inside the reactor were also controllable through proportional integral derivative panel (PID) after that, the percentage conversion of FFAs can be calculated by equation (2). (27)
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The change in conversion degree with amount of catalyst at fixed temperature (30°C) presents three important domains. The first presents a linear increase of conversion up to 86% with 1% of catalyst. In the second, where the amount of catalyst is comprised between 1 - 1.1%, there is a stationary variation. This indicates the optimal quantity of catalyst that gives a limit of 90% conversion. Finally, in the third, we have an expected decrease in the conversion due to the excess of catalyst. This excess leads to hydrolysis of the fatty acids contained in the oil, which moves the transesterification reaction towards the formation of soap (saponification).
Abstract— The application of used vegetable oil as feedstock for the synthesis of biodiesel has been found to be affordable and does not interfere with the food chain. This present study applied L16 Taguchi design to optimize the catalytic transesterification of waste sunflower oil to waste sunflower methyl ester (WSME). The predicted optimized conditions were catalyst: oil ratio of 2.5:1, reaction time of 75 min, reaction temperature of 90 o C, catalyst particle size of 55 µm and methanol:oil ratio of 8:1. The contribution factor of the significant process parameters is found to be 49.04 % for catalyst:oil ratio, 25.32 % for reaction temperature, 18.44 % for catalyst particle size, and 6.65 % for reaction time. The analysis of variance presented a p-value of 0.0047 and a correlation coefficient of 0.9945. The actual fatty acid (FA) conversion is in satisfactory agreement with the predicted value. Thus, the optimization of the percentage FA conversion using Taguchi design generated optimal parametric conditions for the cost-effective and time-saving transesterification of waste sunflower oil to WSME.
Method analyzed total glycerol and free glycerol referred to EN 14105. Sample was used after final washing and drying which the composition of TG, DG, MG and glycerol was analyzed using a Perkin Elmer Gas Chromatography (GC) Model Clarus 500, equipped with a DB-5 HT capillary column (0.53 mm x 5 m) J&W Scientific. The following condition of GC are : the column temperature was started at 50°C held for 1 min, programmed 1 with flow rate at 15°C/min up to 180°C, programmed 2 with flow rate at 7°C/min up to 230°C, programmed 3 used flow rate at 10°C/min up to 370 °C, final temperature held for 5 min, detector temperature at 380°C, carrier gas pressure (hydrogen) at 80 kPa, volume injected of 1 ml .The conversion of FFA in the WCO into FAME was calculated from the mean of acid value (Av) of the oil layer by the following equation .
In the synthesis of methanol via hydrogenation process, one key contributor to the effectiveness of this process is the presence of a suitable catalyst. The most suitable and widely used catalyst is the Cu-based catalyst and its optimal performance is based partly on its thermal characteristics and surface morphology and chemistry. Subsequently, this is dependent on various factors including catalyst synthetic method, metal content and composition. In addition, its thermal strength is also dependent on the heating rate. The effect of these factors are summarised as follows based on the results of the current study:
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We also verified that catalyst ratio influenced the con- version rates in a directly proportional relationship. An- other important point concerns the calcination of niobium acid, all the reactions taking place with catalyst calcined at 100˚C and 300˚C showed higher conversion rates than those with niobium acid pretreated at 500˚C and with non-calcined catalyst. This suggests that the BAS (most
electrochemical reactor operating at room temperature and atmospheric pressure and at a very high faradaic efficiency was demonstrated. We hypothesize that the >100% efficiency is possibly due to the contribution of the NEMCA effect. The GC-Ni electrode was found to be highly selective towards the conversion of CO 2 into ethanol (911 mol.% at longer electrolysis times).
Comparison of results obtained through TPD analysis and other catalytic tests pointed toward the conclusion that in the methanol conversion reaction to DME, the amount of conversion was related to the extent of acidity, while selectivity toward DME and stability of the catalyst depended upon the strength of the catalytic sites being utilized. In other words, as the numbers of sites with strong acidity were reduced, the catalyst selectivity and stability were improved. Ultimately, it was determined that Zr- modified H-ZSM-5 zeolite is an optimum catalyst for dehydration of methanol to DME with high conversion, selectivity and stability.
catalytically converted together with water to a product such as methanol by use of solar irradiation. For this purpose a catalyst shall be developed. EnBW investigates the required boundary conditions to make such a principle interesting with respect to energy and greenhouse gas balance as well as economic evaluations. The assessment of boundary conditions includes the analysis of the whole chain from power generation, CO 2 capture and transport, a virtual photocatalytic reactor, the product purification and
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