响应面法对磁性碳基固体酸催化剂的制备工艺优化研究

为使磁性碳基固体酸催化剂具有更好的催化活性和水热稳定性，利用响应面法对其制备工艺进行优化，以催化玉米芯水解所得的木糖得率为评价指标，选取碳化温度、碳化时间、磺化温度和磺化时间4个显著影响的因素，设计四因素三水平Box-Behnken试验，考察各因素对制备催化剂的影响，并确定最优制备工艺条件。实验结果表明，建立的二次多项式数学模型显著性较高（p=0．0003），相关系数R^2=0．8839，对实验结果具有较好的预测性。在优化的基础上确定磁性固体酸催化剂的最佳制备工艺条件为：碳化温度455℃、碳化时间4．8h、磺化温度107℃和磺化时间10．0h。在此条件下制备的磁性固体酸催化剂催化水解玉米芯所得木糖的得率为39．35％，与模型预测值38．73％有1．60％的误差，说明用此模型来优化磁性固体酸催化剂的制备工艺是合理的。同时，将制备的磁性固体酸催化剂与SBA-15、HZSM-5、Amberlyst-15这3种常见固体酸催化剂对催化玉米芯水解的木糖得率进行比较，结果表明，磁性固体酸催化剂的活性最高，研究价值突出。通过研究，明确制备过程中各因素对磁性碳基固体酸催化剂催化活性和水热稳定性的影响情况，可为后续催化剂设计、改性、载体选择等方面提供理论依据和实验基础

磁性碳基固体酸催化剂的制备及其水解工艺优化研究

采用共沉淀法合成磁性Fe3O4,通过碳化磺化制备核壳结构的磁性固体酸催化剂Fe3O4/C-SO3H,并利用透射电子显微镜(TEM)、傅里叶变换红外光谱仪(FT-IR)、X射线衍射(XRD)、振动样品磁强计(VSM)、元素分析等手段对催化剂特性进行表征分析。以催化玉米芯水解所得的木糖得率为评价指标,对磁性固体酸催化剂催化玉米芯水解工艺条件进行优化研究,得出最佳条件为反应时间10 h、反应温度140℃、催化剂用量1.5 g、固液比(g/mL)2∶50(玉米芯含量为0.5 g),此时木糖得率为51.01%。研究认为,磁性固体酸催化剂催化木质纤维素水解的反应过程为酸催化和吸附过程共同作用,木质纤维素是分级解聚逐步转化,利用两步操作能够最大程度的水解木质纤维素

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel

JUNO sensitivity on proton decay p → ν K + searches*

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this study, the potential of searching for proton decay in the $p\to \bar{\nu} K^+$ mode with JUNO is investigated. The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar{\nu} K^+$ is 36.9% ± 4.9% with a background level of $0.2\pm 0.05({\rm syst})\pm$$0.2({\rm stat})$ events after 10 years of data collection. The estimated sensitivity based on 200 kton-years of exposure is $9.6 \times 10^{33}$ years, which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies