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Bin Zhang Jun Xu Fengtao FanQiang Guo Xiaoqiang TongWenfu Yan Jihong YuFeng Deng Can LiRuren Xu 《Microporous and mesoporous materials》2012,147(1):212-221
The influence of water content on the crystallization of the microporous aluminophosphate AlPO4-11 was investigated by a combination of in situ UV Raman and ex situ XRD and NMR characterizations. Under high water content conditions (Al2O3:H2O = 1:20-69), an AlPO4-5 intermediated formed first and later co-existed with AlPO4-11. In the last stage of crystallization, the crystalline AlPO4-5 completely disappeared and well-crystallized AlPO4-11 was obtained. The position of the three signals observed in the 31P MAS NMR spectra of the isolated solid samples did not change during the hydrothermal treatment, suggesting that the fragments containing the P site in the junction of 6- and 4-membered rings of both AlPO4-5 and AlPO4-11 formed first and that the environments of the P sites were very similar to those in the final structure. A significant increase of Al concentration in liquid media was observed before the appearance of XRD detectable AlPO4-11. Under low water content conditions (Al2O3:H2O = 1:15), the AlPO4-11 was directly crystallized from the initial mixture. In situ Raman spectra showed that the 10-membered rings were complete by the time the transformation of octahedral Al to tetrahedral Al was finished and that the conformation of the protonated di-(i-propyl)amine changed little during the crystallization. The present study showed that the composition of the liquid phase is critical to the formation of a specific structure. 相似文献
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该文评价了黑果枸杞花青素提取物(Anthocyanins extract of Lycium ruthenicum,AEL)的急性毒性和亚急性毒性。采用固定剂量法一次灌胃AEL 8 000 mg/kg进行经口急性毒性试验,观察小鼠毒性反应,记录14 d内一般状态。选取SD大鼠进行30 d喂养试验,记录大鼠体质量和体征变化,实验结束时进行尿液生化指标、血液学指标、血清生化指标检查,并观察脏器形态变化,计算脏体系数和脏脑系数。研究发现:急性毒性试验中,小鼠无不良反应,体质量正常增长,解剖脏器未见明显异常;连续灌胃30 d后,各组大鼠体质量正常增长,未见明显中毒反应;与对照组比较,高剂量组雌性大鼠单核细胞百分比(M%)显著升高(P<0.05),AST/ALT的比值显著降低(P<0.05);高剂量组雄性大鼠血清Cl-、脾脏系数高于对照组(P<0.05)。实验组大鼠其余尿液生化指标、血液学指标、血清生化指标、脏体系数和脏脑系数无明显异常。结果表明:小鼠对AEL的单次灌胃最大耐受剂量不低于8 000 mg/kg;连续灌胃30 d,大鼠未见明显中毒反应,AEL在该实验条件下无急性、亚急性毒性,具有较高的安全性。 相似文献
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Abstract We begin with a review of asymptotic properties of a purely sequential minimum risk point estimation (MRPE) methodology for an unknown mean in a one-parameter exponential distribution under a class of generalized loss functions. This class of powered absolute error loss (PAEL) includes both squared error loss (SEL) and absolute error loss (AEL) plus cost of sampling. We prove the asymptotic second-order efficiency property and asymptotic first-order risk efficiency property associated with the purely sequential MRPE problem. For operational convenience, we then move to implement an accelerated sequential MRPE methodology and prove the analogous asymptotic second-order efficiency property and asymptotic first-order risk efficiency property. We follow up with extensive data analysis from simulations and provide illustrations using cancer data. 相似文献
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Cu ions were incorporated into MgAlPO-11 and ZnAlPO-11 molecular sieves by ion exchange procedure from the Cu acetate solution. The number of the Cu ions in MeAlPO-11 corresponded roughly to the number of the negative charges in the framework produced by the substitution of trivalent aluminium by divalent Mg or Zn cations. Both CuMeAlPOs exhibited constant conversion in NO decomposition in time-on-stream (T-O-S). The turn-over-frequency (T-O-F) values of NO per Cu atom of CuMeAlPO-11 at 770 K are comparable to those of the Cu ions implanted in the cationic sites of high silica ZSM-5 matrix. 相似文献
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Xiaomei Yang Zhusheng Xu Zhijian Tian Huaijun Ma Yunpeng Xu Wei Qu Liwu Lin 《Catalysis Letters》2006,109(3-4):139-145
MgAPO-11 molecular sieves with varying Mg contents synthesized by the hydrothermal method were used as supports for bifunctional
Pt/MgAPO-11 catalysts. MgAPO-11 molecular sieves and the corresponding catalysts were characterized by X-ray diffraction (XRD),
X-ray fluorescence spectroscopy (XRF), temperature-programmed desorption of NH3 (NH3-TPD), differential thermogravimetric (DTG) analysis, temperature-programmed reduction of H2 (H2-TPR), H2 chemisorption and catalytic reaction evaluation. The results indicated that the acidity generated via the substitution of Mg2+ for Al3+ in the framework increased with the Mg content. Acting as acidic components, the MgAPO-11 molecular sieves loaded with Pt
were tested in the hydroisomerization of n-dodecane. Optimum isomer yield was obtained over the Pt/MgAPO-11 catalyst that had neither the highest acidity nor the highest
Pt loading among the tested catalysts. In fact, the activity and the isomer yield both could attain a maximum on 0.5 wt.%
Pt/MgAPO-11 catalysts with differing Mg contents. A lower Mg content resulted in an insufficient acidity, whilst a higher
Mg content weakened the dehydrogenation/hydrogenation function of the Pt. These inappropriate balances between the acidic
and the metallic functions of the catalysts would lead to low activities and isomer yields. On the other hand, the 0.5 wt.%
Pt/MgAPO-11(3) catalyst was found to have a good balance between the acidic and the metallic functions, and thus exhibited
both high activity and isomer yield in comparison with the conventional 0.5 wt.% Pt/SAPO-11 catalyst. 相似文献
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《International Journal of Hydrogen Energy》2022,47(90):38106-38113
The investment costs of water electrolysis represent one key challenge for the realisation of renewable hydrogen-based energy systems. This work presents a technology cost assessment and outlook towards 2030 for alkaline electrolysers (AEL) and PEM electrolysers (PEMEL) in the MW to GW range taking into consideration the effects of plant size and expected technology developments. Critical selected data was fitted to a modified power law to describe the cost of an electrolyser plant based on the overall capacity and a learning/technology development rate to derive cost estimations for different PEMEL and AEL plant capacities towards 2030. The analysis predicts that the CAPEX gap between AEL and PEMEL technologies will decrease significantly towards 2030 with plant size until 1–10 MW range. Beyond this, only marginal cost reductions can be expected with CAPEX values approaching 320–400 $/kW for large scale (greater than 100 MW) plants by 2030 with subsequent cost reductions possible. Learning rates for electrolysers were estimated at 25–30% for both AEL and PEMEL, which are significantly higher than the learning rates reported in previous literature. 相似文献
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采用静态水热法, 在活性胶液中各组分摩尔比为n(R)/ n(ZnO)/ n(Al2O3)/ n(P2O5)/ n(H2O)=1 ∶
x ∶y ∶1.1∶80 (0.5x +y =1)的条件下合成了具有不同锌含量的锌铝磷酸盐分子筛(ZnAPO -11), 利用XRD,
SEM , N2 吸附, MAS -NMR 及ICP-AES 等方法对合成的ZnAPO -11 分子筛进行了表征。结果表明, 当0 ≤n
(ZnO)/n(Al2O3) ≤0 .04 时, 可以合成出具有AEL 结构类型的ZnAPO -11 分子筛, 样品具有较高的结晶度和纯
度;晶体形貌均匀, 呈长条形;锌同晶取代了AlPO4 -11 分子筛上的骨架铝。以正己烷为模型底物, 评价了合成的
ZnAPO-11 分子筛的催化裂解反应活性, 研究结果显示ZnAPO -11 在475 ~ 550 ℃具有反应活性, 其中正己烷的转
化率随接触时间的增加而增加, 反应的表观速率常数随反应温度的升高而增加;正己烷在ZnAPO -11 分子筛上的
催化裂解反应的速率方程中的正己烷浓度项反应级数为1, 表观速率常数与反应温度间的关系可用Arr henius 公式
表示。 相似文献
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