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拼写做的很棒，在平时练习中注意词汇量的积累；从句使用稍显不足，注意个别句子错误；上下文衔接不流畅，文章结构不严谨。
Fig. 2 shows the low angle powder XRD patterns in the range of 2θ from 1 to 10o. The peaks at 2.2, 3.8 and 4.4o in the XRD pattern of MCM-41 (Fig. 2a) are assigned to (100), (110) and (200) reflections related to the hexagonal symmetry lattice [31], confirming highly ordered and hexagonal mesoporous structure of MCM-41. The intensities of (110) and (200) reflections in the pattern of complex support Fe3O4@MCM-41 (Fig. 2b) become weaker while almost disappear in the pattern of Cu(acac)2/n-Bu4NBr/Fe3O4@MCM-41(Fig. 2c). However, the (100) reflection around 2.2o still presents in the patterns of support and supported catalyst. The observation of (110) reflection indicates that complex support and supported catalyst still possess hexagonal mesoporous structure but with decreased order, which might be ascribed to the location of Fe3O4 and active species inside the framework of MCM-41. The powder XRD patterns in the range of 2θ from 10 to 80o are shown in Fig. 3. The peaks at 30.2o, 35.7o, 43.2o, 53.7o, 57.1o and 62.9o in the patterns are associated with (220), (311), (400), (422), (511) and (440) reflections assigned to the inverse cubic spinel structure of Fe3O4 [32]. The observation of the characteristic diffraction peaks related to Fe3O4 indicates almost no change in the structure of Fe3O4 after combining with MCM-41 as well as supporting Cu(acac)2 and/or n-Bu4NBr. The Fig. 3 also shows that the characteristic diffraction peaks belonging to Cu(acac)2 (JCPDS: 11-800) are absent in the patterns of the samples obtained via the introduction of Cu(acac)2 alone or not (Fig. 3b-3d ), even with relatively high Cu loading of 4.5 wt.% (Fig. 3d). It may be ascribed to high dispersion of active species into the mesoporous channels resulted from the ordered hexagonal structure of MCM-41. The characteristic of n-Bu4NBr (JCPDS: 26-1539) at 18.2 and 22.7o were observed in the pattern of supported catalyst with 7.0 wt.% Br loading obtained via supporting n-Bu4NBr alone but disappear in the pattern of Cu(acac)2/n-Bu4NBr/Fe3O4@MCM-41 with 5.9 wt.% Br loading, which may be ascribed to the relatively lower content of n-Bu4NBr in the latter. No observation of the characteristic peaks of active species is consistent with the results shown in Fig. 2, further confirming part of active species enters into the framework of MCM-41. It may be helpful to prevent the loss in active species and thus make the catalytic performance of supported catalyst relatively stable.
