Xiong Zheng,Ying Zhang,Maogang He,Lili Liang,Xinxin He
Fatty acid ethyl esters (FAEEs) are the main components in some biodiesels, which are important alternatives of fossil fuels. In this paper, we carry out the measurements of the speed of sound in two FAEEs at the temperatures from (293.15 to 473.15) K and at the pressures up to 10 MPa, including saturated liquid and compressed liquid. The relative expanded uncertainty in the speed of sound is estimated to be less than 1.0% with coverage factor of k to be 2. The data in saturated liquid and compressed liquid are fitted into polynomials. For saturated liquid, the D AAD is 0.16% for ethyl hexanoate and 0.09% for ethyl octanoate. For compressed liquid, the D AAD is 0.31% for ethyl hexanoate and 0.16% for ethyl octanoate. The data were also used to assess the predictive ability of Wada’s model.
The thermal diffusivities of 2-ethoxy-2-methylpropane (ETBE) and 2-methoxy-2-methylbutane (TAME) (mass purity > 0.990, GC) were measured by the dynamic light scattering method. The investigated p–T regions are T = (293 to 523) K and p = (4 to 10) MPa, including saturated liquid, saturated vapor, and liquid. The expanded relative uncertainty in thermal diffusivity was estimated to be less than 2.4% over the whole investigated range. The influences of temperature and pressure on thermal diffusivity were presented. The empirical correlation of thermal diffusivities for both saturated liquid/vapor and liquid were also proposed with absolute average relative deviations (AARDs) of 0.22 and 0.26% for saturated-liquid ETBE and TAME, 0.13 and 0.20% for saturated-vapor ETBE and TAME, and 0.23 and 0.69% for liquid ETBE and TAME, respectively.
Highly dispersed palladium nanoparticles (NPs) supported on UiO-66 as catalyst for CO 2 methanation were prepared by supercritical fluid deposition (SFD). As a result, the most suitable Pd precursor salt and co-solvent are Na 2 PdCl 4 and ethanol/DMF, respectively. The best SFD process condition to deposit the Pd precursor on UiO-66 is 40 °C, 10 MPa and 2 h. Under the above condition, 4% Pd/UiO-66 exhibits the highest activity with 53% of CO 2 conversion and 95% of CH 4 selectivity while the turnover frequency (TOF) value is 3669.4 h −1 . The catalysts were characterized by XRD, BET, TEM, XPS, TGA, CO-DRIFTS and ICP-OES to investigate the structure–activity relationship. The 4% Pd/UiO-66 with the average size of 2.2 nm of Pd prepared in assistance of supercritical fluid behaved the similar activity as the 6%Pd/UiO-66 with average size of 9.7 nm of Pd prepared by sol–gel method. It is showed prospect of technique for reducing noble metal loading resulting from high dispersion effect.
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