我们感谢中国科学技术部国家重点研究 & 开发项目 (2016YFB0600305)、国家自然科学基金 (21573031 和21373038号) 提供的财政支持, 项目为大连市 (2016RD09) 和香港科技高等教育学院优秀人才 (SG1617105 和 SG1617127)。

警告:针对本白皮书所述化学品的正确处理方法、性质和毒性, 请参阅有关材料安全数据表 (MSDS)。使用的一些化学物质是有毒和致癌的, 必须特别注意。纳米材料可能会造成安全隐患和健康影响。应避免吸入和皮肤接触。必须采取安全防范措施, 如在油烟机中进行催化剂合成和用高压釜反应器进行催化剂性能评估。必须佩戴个人防护设备。
1. 制备镍0.97铌0.03O 催化剂, 其中 Nb: (镍 + 铌) 摩尔比率等于0.03
<ol><li>将0.161 克草酸铌 (V) 水合物与2.821 克硝酸镍混合在100毫升的去离子水中, 在250毫升的三颈圆底烧瓶中装有搅拌棒。</li>
	<li>搅拌溶液在 50 rpm 和70°c, 以溶解化合物, 直到沉淀消失, 使用一个加热磁力搅拌器。</li>
	<li>将温度迅速提高到80摄氏度, 速度为2摄氏度/分钟。</li>
	<li>加入混合基本溶液 [氢氧化铵 (50 毫升, 1.0 米) 和氢氧化钠 (50 毫升, 0.2 米)] 到反应混合物滴状直到镍/铌溶液的 pH 值达到9.0。</li>
	<li>搅拌反应混合物时, 将温度提高到120摄氏度, 在2摄氏度/分钟。</li>
	<li>搅拌反应混合物隔夜在 50 rpm 在120°c, 直到完全消失的绿色颜色的解决方案。</li>
	<li>进行电感耦合等离子体-光发射光谱 (ICP) 分析, 以评估溶液中剩余 Ni2 +和铌5 +离子的浓度, 确保剩余镍的完全沉淀硝酸盐.</li>
	<li>用 Büchner 瓶过滤收集固体。在20分钟内重复添加2升去离子水, 以去除残留 Na+阳离子, 以洗涤固体。</li>
	<li>在手表玻璃中收集固体。干燥的固体在110°c 12 小时在干燥的烤箱。</li>
	<li>将合成空气中的固体加热 (20 毫升/分钟2和80毫升/分 N2) 的煅烧, 在450摄氏度为 5 h 在管式炉中。在使用高温反应之前, 检查所有玻璃器皿是否有缺陷。</li>
	<li>煅烧后, 获得1克镍0.97铌0.03O 催化剂。使用适当的防护设备, 如安全眼镜, 手套, 实验室大衣和油烟机, 以执行纳米晶反应, 由于潜在的安全隐患和健康影响的纳米材料。</li>
</ol>2. 制备镍0.92铌0.08O 催化剂, 其中 Nb: (镍 + 铌) 摩尔比率等于0.08
<ol><li>除前两个步骤外, 此过程与1类似:<ol>
<li>将0.43 克草酸铌 (V) 水合物溶解在100毫升的去离子水中。</li>
		<li>分别在100毫升去离子水中溶解2.675 克硝酸镍。</li>
	</ol>
</li>
</ol>3. 制备镍0.85铌0.15O 催化剂, 其中 Nb: (镍 + 铌) 摩尔比率等于0.15
<ol><li>除前两个步骤外, 该过程与1类似:<ol>
<li>将0.807 克草酸铌 (V) 水合物溶解在100毫升的去离子水中。</li>
		<li>分别在100毫升去离子水中溶解2.472 克硝酸镍。</li>
	</ol>
</li>
</ol>4. 制备镍0.80铌0.20O 催化剂, 其中 Nb: (镍 + 铌) 摩尔比率等于0.20
<ol><li>除前两个步骤外, 该过程与1类似:<ol>
<li>将1.076 克草酸铌 (V) 水合物溶解在100毫升的去离子水中。</li>
		<li>分别在100毫升去离子水中溶解2.326 克硝酸镍。</li>
	</ol>
</li>
</ol>5. 使用化学沉淀法制备 Nb2O5
<ol><li>煅烧铌酸 (Nb2O5·nH2O) 在合成空气中为 5 h 在450°c 获得纯 Nb2O5粒子。 注: 使用 X 射线粉末衍射 (XRD) 分析确认完成反应, 其中 nb2O5·nH2o 为无定形, nb2o5为晶体。根据分析, 在450摄氏度煅烧5小时足够完成反应。</li>
</ol>6. 合成β O-4 木质素模型化合物, 2-(2-methoxyphenoxy)-1-phenylethan-1-一
<ol><li>将 bromoacetophenone (9.0 克, 45 毫摩尔) 和 2-苯酚 (6.6 克, 53 毫摩尔) 在200毫升的甲基酰胺 (DMF) 中溶解, 用磁力搅拌器将其放在一个多锥瓶中。使用适当的防护设备和通风罩, 使用腐蚀性和致癌性的化学品和试剂进行反应。</li>
	<li>将上述 DMF 溶液与氢氧化钾 (3.0 克, 53 毫摩尔) 混合, 用磁性搅拌器在室温下以 50 rpm 的方式搅拌混合物。</li>
	<li>用分离漏斗提取200毫升的 H2O 和600毫升乙醚 (1:3, v/v) 的混合物溶液。获得溶液的上二乙基醚层。</li>
	<li>添加 MgSO4 (10 克) 以吸收二乙基醚溶液的水分。筛选 MgSO4以使用过滤纸和漏斗获得二乙醚溶液。</li>
	<li>用旋转蒸发器在0.08 兆帕斯卡的减压下除去二乙基醚溶液后, 将残留物溶解在5毫升乙醇中。</li>
	<li>慢慢蒸发乙醇溶剂, 结晶10毫升烧杯中的产品。获得产品 (11.5 克) 为黄粉, 产品产量为 90%, 基于 bromoacetophenone。从1h 核磁共振分析, 1h 核磁共振 (亚砜): δ 3.78 (s, 3H, 秒3), 5.54 (s, 2H, CH2), 6.82-8. 01 (m, 9H, 芳香) ppm。17
</li>
</ol>7. 木质素衍生芳香醚的加氢脱氧
注: 本实验中选用的木素衍生芳烃醚为甲醚, 催化剂为 Ni0.92铌0.08o 使用适当的保护设备和油烟机, 使用致癌试剂进行反应。
<ol><li>用加热器和磁力搅拌器装备一个50毫升不锈钢蒸压釜。</li>
	<li>将在 H2大气中的高压釜反应器中从步骤2获得的 Ni0.92铌0.08O 催化剂 (1 克) 减少400摄氏度, 然后在氩 (2 毫升/分钟) 一夜之间钝化催化剂。</li>
	<li>将甲醚 (1.1712 克, 8 wt%) 分解为 n-decane (20 毫升), 使用 n-烷基 (0.2928 克, 2 wt%) 作为定量气相色谱 (GC) 分析的内部标准。</li>
	<li>迅速将还原催化剂 (0.1 克) 引入高压釜反应器, 以避免长时间接触空气 (< 5 分钟)。</li>
	<li>密封釜式反应器, 用 H2重复清除 (3 次, 3 兆帕压力) 以消除空气, 然后在大气压下反应混合物。</li>
	<li>设置搅拌速度为 700 rpm。</li>
	<li>加热到期望的温度在160-210 °c 在2°c/分钟, 加压釜反应器到 3 MPa 并且设置零时间点 (t = 0)。 注: 本报告适用于160-210 摄氏度的温度范围。</li>
	<li>随后, 将混合物冷却到室温在10摄氏度/分钟, 并分析脱氧产品使用气相色谱与质量选择检测器。17
</li>
	<li>根据以下方程式确定木质素模型化合物的转化: <img alt="Equation 1" src="/files/ftp_upload/56987/56987eq1.jpg">
</li>
	<li>根据以下公式确定产品选择性: <img alt="Equation 2" src="/files/ftp_upload/56987/56987eq2.jpg">
</li>
</ol>

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Res. 18 (5), 1-12 (2016).</li><li>Wang, K., Yang, L., Zhao, W., Cao, L., Sun, Z., Zhang, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+facile+synthesis+of+copper+nanoparticles+supported+on+an+ordered+mesoporous+polymer+as+an+efficient+and+stable+catalyst+for+solvent-free+sonogashira+coupling+Reactions.">A facile synthesis of copper nanoparticles supported on an ordered mesoporous polymer as an efficient and stable catalyst for solvent-free sonogashira coupling Reactions.</a> Green Chem. 19, 1949-1957 (2017).</li><li>Song, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-Selectivity+Electrochemical+Conversion+of+CO2+to+Ethanol+using+a+Copper+Nanoparticle/N-Doped+Graphene+Electrode.">High-Selectivity Electrochemical Conversion of CO2 to Ethanol using a Copper Nanoparticle/N-Doped Graphene Electrode.</a> Chemistry Select. 1, 6055-6061 (2016).</li></ol>

我们没有什么可透露的。

制备镍掺杂块状铌氧化物纳米微粒的常用方法之一是旋转蒸发法。9通过在旋转蒸发过程中采用各种压力和温度条件, 将镍铌 O 颗粒的沉淀与溶剂的缓慢去除进行贸易。与旋转蒸发法相比, 本研究报告的化学沉淀法在制备纳米微粒时越来越受到重视, 因此不需要去除溶剂。在典型的化学沉淀法中制备催化剂, 在长期的金属盐溶液中加入碱性溶液是必要的。21在我们的研究中, 采用了氢氧化铵和氢氧化钠溶液的混合物作为沉淀剂。化学沉淀法的关键步骤之一是添加沉淀剂的速度。22,23必须注意控制沉淀剂的添加速度,即, 基本混合物, 最好以每秒一滴的速度控制。如有可能, 蠕动泵可用于精确控制沉淀剂的添加。
除加法率之外, 温度控制是成功的降雨雪的另一个重要关键, 当被准备的金属氧化物的形态学高度依赖于准备的温度。虽然纳米粒子的形貌与相关的催化性能之间的相关性尚不清楚, 但最优化的制备温度是开发高效催化剂的关键。
由于 Brønsted 和 Lewis 酸的位置是 HDO 过程转换酚和含氧芳烃为碳氢化合物所必需的, 因此,17对酸性部位的含量进行优化也是提高催化性能的关键因素。纳米.根据纳米粒子化学沉淀法的相关力学研究, Brønsted 的数量对催化剂上剩余水的含量有很高的依赖性。24因此, 控制催化剂的干燥期和煅烧温度也是该协议中的关键步骤, 以优化催化剂的催化性能。
与其他常用的纳米微粒制备方法相比, 化学沉淀法在制备纳米微粒方面得到了越来越多的重视。这可能是因为这不需要去除溶剂的准备。此外, 该方法还能促进金属成分的均匀分散, 并可广泛用于制备相对较大表面积的纳米粒子。17但是, 这种方法最好是用相对较高的金属离子浓度 (如过渡金属元素) 制备金属氧化物催化剂。25,26,27因此, 建议不要使用此方法制备碱性金属氧化物。
然后用氢氧化钠和氢氧化铵水溶液在 pH 值为9的混合物处理悬浮液, 使样品中残留的镍2 +和铌5 +阳离子完全沉淀, 然后用去离子水洗涤。重复删除过量 Na+阳离子。随后在450摄氏度的合成空气中煅烧后, 制备并分析了 Nix铌1-xO 纳米粒子。
为合成的镍x铌1-xO (表 1) 收集的表面积、孔隙体积和大小表明, 化学沉淀合成通过将适当的铌比例纳入 NiO (nb: Ni 比 < 0.087) 可以有效地增加了材料的表面积, 因为草酸铌被用作前驱体。这也支持的事实, 更多孔结构可以形成的化学分解水合草酸镍与有机性质,9 , 在 X 射线衍射模式 (图 1) 中观察到的。但是, 当 nb: ni 比率提高到0.15 和0.25 时, nix铌1 xO 的表面积会显著降低。这可能是由于在样品中形成大块样晶粒。谢瑞公式用于计算所有制备的混合氧化物的晶粒尺寸。可以得出结论, 晶粒的大小与相应的表面积密切相关。我们在别处展示了铌: Ni 比是决定氧化物对木质素衍生有机化合物加氢脱氧的催化活性的关键因素。含 nb 率高 (nb: 镍 > 0.087) 的非活动 NiNb2O6种由铌和 NiO 非晶相反应形成, 导致 nio 的聚集, 从而获得了较低表面积的催化剂。含铌含量低 (nb: 镍≤ 0.087), 添加草酸铌可增加催化剂的表面积。这是由于形成的草酸镍延缓了 NiO 晶粒的晶体生长, 从而得到了更高比表面积的催化剂。另一方面, 对于含铌量较低的催化剂, 非晶铌2O5可以促进 nio 晶粒在表面的分散, 从而抑制 nio 晶粒的聚集。镍0.92Nb0.08O 的大表面积 (173 米2/克), 由类似褶皱的薄片组成, 表现出对环己烷甲醚加氢脱氧的最佳活性和选择性。
总结了化学沉淀法制备镍铌氧催化剂的方法。虽然这种方法需要较高浓度的金属离子溶液, 但发现它成功地准备了催化剂与更高的表面积, 比较那些从其他方法获得。此外, 新制备的纳米粒子在甲醚加氢脱氧环己烷中表现出良好的催化活性。目前正在研究其在其他催化系统如加氢方面的应用。此外, 预期还可进一步将类似的战略应用于其他不同的混合镍氧氧化物或其他纳米材料的制备, 如铜2 +, Co2 + , 具有高比表面积的各种有用如酒精和水的氧化和催化偶联反应等应用。28,29,30

纳米复合材料的制备因其在各个领域的重要应用而受到越来越多的关注。为制备镍铌 O 混合氧化物纳米粒子,1,2,3,4,5,6不同的方法已经开发, 如干混合法,7, 8蒸发方法、9、10、11、12、13溶胶凝胶法、14热分解法、15和自动燃烧。16在典型的蒸发方法9中, 含有适当数量的金属前体、硝酸镍六水合物和草酸铌铵的水溶液加热70摄氏度。在溶剂去除和进一步烘干和煅烧后, 得到了混合氧化物。这些氧化物催化剂对乙烷的氧化脱氢 (脱氢) 具有良好的催化活性和选择性, 这与在 NiO 晶格中加入铌阳离子引起的电子和结构重排有关。.11插入 Nb 会大幅减少亲氧的种类, 这是对乙烷12氧化反应的负责。因此, 这种方法的推广已经在制备不同类型的混合镍氧氧化物, 在那里我 = 李, 镁, 铝, Ga, Ti 和 Ta。13发现金属掺杂的变化可以改变 NiO 的 unselective 和亲氧自由基, 从而系统地调节脱氢的活性和对乙烷的选择性。然而, 通常这些氧化物的表面积相对较小 (< 100 米2/克), 这是由于扩展的相隔离和形成大 Nb2O5晶粒, 从而妨碍了它们在其他催化应用程序.
干混法, 又称固态磨削法, 是制备混合氧化物催化剂的另一种常用方法。由于催化材料是以无溶剂的方式获得的, 这种方法为混合氧化物的制备提供了一个有前景的绿色和可持续的替代方案。该方法获得的最高表面积为镍80铌20在煅烧温度为250摄氏度的172米2/克。8然而, 这种固态方法不可靠, 因为反应物在原子尺度上没有很好的混合。因此, 为了更好地控制化学均匀性和特定粒径分布和形貌, 目前仍在寻找其他合适的方法制备镍铌 O 混合氧化物纳米粒子。7
在纳米粒子发展的各种策略中, 化学沉淀是发展催化剂的一种有希望的方法, 因为它允许金属离子的完全沉淀。同时, 用该方法制备较高表面积的纳米粒子。为了提高镍铌纳米粒子的催化性能, 本文报道了化学沉淀法合成高表面积镍铌 o 型混合氧化物催化剂的协议。我们证明, 铌: 镍摩尔比是决定氧化物催化活性的关键因素, 对木质素衍生有机化合物的加氢脱氧。高铌: 镍比0.087 以上, 非活动 NiNb2O6种形成。Ni0.92铌0.08O 具有最大的表面积 (173 米2/克), 它具有折叠状的薄片结构, 并显示了对甲醚到环己烷加氢脱氧的最佳活动和选择性。

<table>
	<tbody>
		<tr>
			<td>Niobium(V) oxalate hydrate, 98%</td>
			<td>Alfa</td>
			<td>L04481902</td>
			<td></td>
		</tr>
		<tr>
			<td>Nickel nitrate hexahydrate, 99%</td>
			<td>Aladdin</td>
			<td>N108891</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium hydroxide, 98%</td>
			<td>Aladdin</td>
			<td>S111501</td>
			<td></td>
		</tr>
		<tr>
			<td>Ammonium hydroxide, 23-25%</td>
			<td>Aladdin</td>
			<td>A112077</td>
			<td></td>
		</tr>
		<tr>
			<td>Anisole, 99%</td>
			<td>Sinopharm</td>
			<td>81001728</td>
			<td></td>
		</tr>
		<tr>
			<td>Diphenyl ether, 98%</td>
			<td>Aladdin</td>
			<td>D110644</td>
			<td></td>
		</tr>
		<tr>
			<td>Phenol, 98%</td>
			<td>Sinopharm</td>
			<td>100153008</td>
			<td></td>
		</tr>
		<tr>
			<td>2-Methoxyphenol, 98%</td>
			<td>Sinopharm</td>
			<td>30114526</td>
			<td></td>
		</tr>
		<tr>
			<td>Vanillin, 99.5%</td>
			<td>Sinopharm</td>
			<td>69024316</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium hydroxide, AR</td>
			<td>Aladdin</td>
			<td>P112284</td>
			<td></td>
		</tr>
		<tr>
			<td>N,N-Dimethylformamide, 99.5%</td>
			<td>Sinopharm</td>
			<td>40016462</td>
			<td></td>
		</tr>
		<tr>
			<td>2-Bromoacetophenone,98%</td>
			<td>Aladdin</td>
			<td>B103328</td>
			<td></td>
		</tr>
		<tr>
			<td>Diethyl ether,99.5%</td>
			<td>Sinopharm</td>
			<td>10009318</td>
			<td></td>
		</tr>
		<tr>
			<td>Decane,98%</td>
			<td>Aladdin</td>
			<td>D105231</td>
			<td></td>
		</tr>
		<tr>
			<td>Dodecane,99%</td>
			<td>Aladdin</td>
			<td>D119697</td>
			<td></td>
		</tr>
		<tr>
			<td>Niobic acid</td>
			<td>CBMM</td>
			<td>1313968</td>
			<td></td>
		</tr>
		<tr>
			<td>Heating and Drying Oven</td>
			<td></td>
			<td></td>
			<td>DHG Series (shanghai jinghong laboratory instrument co. ltd)</td>
		</tr>
		<tr>
			<td>Autoclave Reactor</td>
			<td></td>
			<td></td>
			<td>CJF-0.05&#8212;0.1L (Dalian Tongda Equipment Technology Development Co., Ltd)</td>
		</tr>
		<tr>
			<td>Tube&#160;furnace</td>
			<td></td>
			<td></td>
			<td>SK2-1-10/12 (Luoyang Huaxulier Electric Stove Co., Ltd)</td>
		</tr>
		<tr>
			<td>Heating magnetic stirrer</td>
			<td></td>
			<td></td>
			<td>DF-101 (Yu Hua Instrument Co. Ltd.)</td>
		</tr>
		<tr>
			<td>Rotary evaporator</td>
			<td></td>
			<td></td>
			<td>RE-3000A (Shanghai Yarong Biochemical Instrument Factory)</td>
		</tr>
		<tr>
			<td>Synthetic air</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrogen gas</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Argon gas</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

chemical precipitation method for the synthesis of nb2o5 modified bulk nickel catalysts with high specific surface area

我们演示了一种用海绵状和褶皱状纳米结构合成镍x铌1-xO 催化剂的方法。通过改变 Nb: ni 比, 用化学沉淀法制备了一系列不同原子组成 (x = 0.03、0.08、0.15 和 0.20) 的镍x铌1 xO 纳米粒子。这些镍x铌1 xO 催化剂的特点是 x 射线衍射、x 射线光电子能谱和扫描电镜。研究发现镍的0.97铌0.03O 和 ni0.92Nb0.08o 在 NiO 表面上的海绵状和褶皱状外观, 以及这些 Nix铌1 xO 催化剂的较大表面积, 与散装nio.镍0.92铌0.08O 型催化剂可获得173米2/克的最大表面积。此外, 还研究了利用合成的 Ni0.92铌0.08O 催化剂对木质素衍生化合物的催化 hydroconversion。

x 射线衍射 (XRD) 模式 (图 1和图 2), 下注表面积, 用氢 (H2-TPR) 的温度编程还原氢, 扫描电子显微镜 (SEM) 配有能量色散 X 射线 (EDX) 分析仪、X 射线光电子能谱 (XPS) 是为纳米 NiO、镍铌 O 和 Nb2O5氧化物17 (图 3和图 4) 收集的。采用 XRD、SEM 和 XPS 等方法确定了纳米结构的相和形貌。在表 1中收集了镍铌 O 混合氧化物的物理化学性质。17
对催化剂的结构进行了以前的报道和讨论。17为硝酸镍和水合铌 (V) 草酸盐化学沉淀形成的混合氧化物所收集的 X 射线衍射模式 (图 1) 与水合草酸镍 (JCPDS 25-0581) 的观测结果吻合较好。.用混合氧化物沉淀2小时在700摄氏度煅烧后, 在26.8°、35.2°和 52.9° (JCPDS 76-2355) 2θ中观察到的峰值对应于结晶 NiNb2O6阶段。
在450°c (图 2) 煅烧5小时后, 为合成的 Nix铌1-xO 纳米粒子收集的 X 射线衍射图案, 显示位于37.1°、43.2°、62.5°、74.8°和 78.7°2θ的主要衍射峰, 对应于(111)、(200)、(220)、(311) 和 (222) reﬂections 分别。这是一个很好的协议水晶 NiO bunsenite 结构 (JCPDS 89-7130)。此外, 人们清楚地注意到, 低强度的宽背景峰出现在约26°与铌负载增加, 这是由于非晶铌氧化物的出现, 由于化学沉淀拥有 nb5 +和羟基离子18。在700摄氏度煅烧时, 在镍-铌-氢0.8铌0.2O 的 X 射线衍射图中观察到与 ni-nb 混合相对应的峰值, 表明在450°c、19的煅烧后, 非晶态存在, 而不是晶态镍铌复合相。据记载, 高铌的含量可能导致混合相镍铌 O 的形成,例如NiNb2O6, Ni3Nb2o8和 Ni4Nb2O9, 这将减少催化能力。
扫描电镜分析显示镍的x铌1-xO 纳米粒子从 NiO (图 3) 的表面形貌显著不同。与纯 nio 的 deﬁned nanosheet 晶体结构形成鲜明对比的是, 在镍0.97铌0.03O 和 ni0.92nb 的薄板状 NiO 表面上明显可见褶皱状和海绵状的外观.分别为 0.08 O。9由于镍2 + (0.69 Å) 和 Nb5 + (0.64 Å) 阳离子的可比离子半径, 因此, 由于在 NiO 晶格结构中加入了铌, 海绵状种类被确定为镍铌固体溶液。9,20因此, 由于 Nb 的增加, 在镍0.85铌0.15o 和镍0.8Nb0.2晶粒纳米粒子上观察到的海绵状/块状外观和圆形小空隙数较少示例中的内容。此外, 能量色散 X 射线图表明, 铌氧化物是良好的分散在散装 NiO 样品 (图 4)。它的铌富集表面进一步证实由更大的表面 Nb: 镍比的镍0.92铌0.08O 样品 (0.11/0.92), 与散装理论价值 (0.08/0.92)。这可以解释的事实, 即制备的镍铌 O 的表面富含镍纳米粒子。
以甲醚加氢脱氧为模型反应, 对制备的镍铌 O 金属氧化物的催化性能进行了试验研究。反应是在 3 MPa 和160摄氏度的高压釜反应器中进行的。0.1 克的 Ni0.92铌0.08O 催化剂被放置在混合物的8甲醚% 和20毫升n-decane。2小时后, 从甲醚到环己烷有31.8% 的选择性, 获得95.3% 的转化率。12小时后, 甲醚完全转化为纯环己烷。并研究了温度对催化性能的影响, 而不是延长反应时间。在2小时之内, 如果温度设定在200°c 而不是160°c, 甲醚完全地被转换了成环己烷。目前的研究重点是对其他具有较高分子量的木素衍生模型化合物的转化, 以研究这种催化剂的加氢脱氧能力。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/56987/56987fig1.jpg"> 图1。将硝酸镍和铌 (V) 草酸盐混合在水中, 在70摄氏度和煅烧后700摄氏度后形成沉淀的 XRD 模式.JCPDS 是粉末衍射标准数据库联合委员会。JCPDS 76-2355 是 NiNb2O6材料的标准 XRD 参考模式。JPCDS 25-0581 是草酸镍水合物材料的标准 XRD 参考模式。此图已由少华金等) 修改。17<a href="//cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56987/56987fig1large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/56987/56987fig2.jpg"> 图2。镍铌 O 混合氧化物催化剂在空气中煅烧450摄氏度后的 XRD 模式 5 h.此图已由少华金等) 修改。17<a href="//cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56987/56987fig2large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/56987/56987fig3.jpg"> 图3。NiO 和镍铌 O 混合氧化物的扫描电镜显微照相。此图已从少华金等中修改。17<a href="//cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56987/56987fig3large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/56987/56987fig4.jpg"> 图4。扫描电子显微照片, x 射线图和能量色散 x 射线分析扫描电镜.a)扫描电子显微照片镍0.92Nb0.08O. b) x 射线图。c) x 射线图d) x 射线图的 Nb. e)能量色散 x 射线 (EDX) 结果镍0.92Nb0.08O 样品。此图已由少华金等) 修改。17<a href="//cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56987/56987fig4large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always"><tbody>
<tr>
<td>催化剂</td>
			<td>铌/镍比</td>
			<td>S下注(m2/g)</td>
			<td>d (nm)</td>
			<td>V总计(cm3/g)</td>
			<td>微晶尺寸 (nm)a</td>
		</tr>
<tr>
<td>nio</td>
			<td>0</td>
			<td>136</td>
			<td>18</td>
			<td>0.61</td>
			<td>9。3</td>
		</tr>
<tr>
<td>Ni0.97Nb0.03O</td>
			<td>0.031</td>
			<td>158</td>
			<td>16。5</td>
			<td>0.65</td>
			<td>8</td>
		</tr>
<tr>
<td>Ni0.92Nb0.08O</td>
			<td>0.087</td>
			<td>173</td>
			<td>9。6</td>
			<td>0.41</td>
			<td>5。4</td>
		</tr>
<tr>
<td>Ni0.85Nb0.15O</td>
			<td>0.176</td>
			<td>139</td>
			<td>12。5</td>
			<td>0.43</td>
			<td>11。8</td>
		</tr>
<tr>
<td>Ni0.80Nb0.20O</td>
			<td>0.25</td>
			<td>110</td>
			<td>12</td>
			<td>0.33</td>
			<td>14。5</td>
		</tr>
<tr>
<td>Nb2O5·nH2o</td>
			<td>-</td>
			<td>122</td>
			<td>6。7</td>
			<td>0。2</td>
			<td>-</td>
		</tr>
<tr>
<td colspan="6">
a由考虑 NiO (200) 峰值较高强度确定。</td>
		</tr>
</tbody></table>表1。NiO 的物理化学性质, Nb2O5和镍铌 O 混合氧化物.本表已从少华金等。17

Watch this Scientific Journal Video about Chemical Precipitation Method for the Synthesis of Nb2O5 Modified Bulk Nickel Catalysts with High Specific Surface Area at JoVE.com

Chemical Precipitation Method for the Synthesis of Nb2O5 Modified Bulk Nickel Catalysts with High Specific Surface Area

本文介绍了化学沉淀法合成海绵状和褶皱状镍1-x铌xO 纳米粒子的一种协议。

化学沉淀法合成铌2O5改性高比表面积镍催化剂

We demonstrate a method for the synthesis of NixNb1-xO catalysts with sponge-like and fold-like nanostructures. By varying the Nb:Ni ratio, a series of ...

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Chemical Precipitation Method for the Synthesis of Nb2O5 Modified Bulk Nickel Catalysts with High Specific Surface Area

11.7K 次观看.  Dalian University of Technology. 本文介绍了化学沉淀法合成海绵状和褶皱状镍1-x铌xO 纳米粒子的一种协议。

视频: Chemical Precipitation Method for the Synthesis of Nb2O5 Modified Bulk Nickel Catalysts with High Specific Surface Area

Gyroid Nickel Nanostructures from Diblock Copolymer Supramolecules

Nanoporous metal foams possess a unique combination of properties - they are catalytically active, thermally and electrically conductive, and furthermore, have high porosity, high surface-to-volume and strength-to-weight ratio. Unfortunately, common approaches for preparation of metallic nanostructures render materials with highly disordered architecture, which might have an adverse effect on their mechanical properties. Block copolymers have the ability to self-assemble into ordered nanostructures and can be applied as templates for the preparation of well-ordered metal nanofoams. Here we describe the application of a block copolymer-based supramolecular complex - polystyrene-block-poly(4-vinylpyridine)(pentadecylphenol) PS-b-P4VP(PDP) - as a precursor for well-ordered nickel nanofoam. The supramolecular complexes exhibit a phase behavior similar to conventional block copolymers and can self-assemble into the bicontinuous gyroid morphology with two PS networks placed in a P4VP(PDP) matrix. PDP can be dissolved in ethanol leading to the formation of a porous structure that can be backfilled with metal. Using electroless plating technique, nickel can be inserted into the template&#39;s channels. Finally, the remaining polymer can be removed via pyrolysis from the polymer/inorganic nanohybrid resulting in nanoporous nickel foam with inverse gyroid morphology.

This article describes the preparation of well-ordered nickel nanofoams via electroless metal deposition onto nanoporous templates obtained from self-assembled diblock copolymer based supramolecules.

Gyroid镍纳米结构的嵌段共聚物超分子

Nanoporous metal foams possess a unique combination of properties - they are catalytically active, thermally and electrically conductive, and furthermore, ...

科研

化学

A Method to Manipulate Surface Tension of a Liquid Metal via Surface Oxidation and Reduction

Controlling interfacial tension is an effective method for manipulating the shape, position, and flow of fluids at sub-millimeter length scales, where interfacial tension is a dominant force. A variety of methods exist for controlling the interfacial tension of aqueous and organic liquids on this scale; however, these techniques have limited utility for liquid metals due to their large interfacial tension.
Liquid metals can form soft, stretchable, and shape-reconfigurable components in electronic and electromagnetic devices. Although it is possible to manipulate these fluids via mechanical methods (e.g., pumping), electrical methods are easier to miniaturize, control, and implement. However, most electrical techniques have their own constraints: electrowetting-on-dielectric requires large (kV) potentials for modest actuation, electrocapillarity can affect relatively small changes in the interfacial tension, and continuous electrowetting is limited to plugs of the liquid metal in capillaries.
Here, we present a method for actuating gallium and gallium-based liquid metal alloys via an electrochemical surface reaction. Controlling the electrochemical potential on the surface of the liquid metal in electrolyte rapidly and reversibly changes the interfacial tension by over two orders of magnitude ( &#820;500 mN/m to near zero). Furthermore, this method requires only a very modest potential (&#60; 1 V) applied relative to a counter electrode. The resulting change in tension is due primarily to the electrochemical deposition of a surface oxide layer, which acts as a surfactant; removal of the oxide increases the interfacial tension, and vice versa. This technique can be applied in a wide variety of electrolytes and is independent of the substrate on which it rests.

We present a method to control the interfacial energy of a liquid metal in an electrolyte via electrochemical deposition (or removal) of a surface oxide layer. This simple method can control the capillary behavior of gallium-based liquid metals by tuning the interfacial energy rapidly, significantly, and reversibly using modest voltages.

方法通过表面氧化还原操纵液态金属的表面张力

Controlling interfacial tension is an effective method for manipulating the shape, position, and flow of fluids at sub-millimeter length scales, where ...

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives

Molecules bearing trifluoromethoxy (OCF3) group often show desired pharmacological and biological properties. However, facile synthesis of trifluoromethoxylated aromatic compounds remains a formidable challenge in organic synthesis. Conventional approaches often suffer from poor substrate scope, or require use of highly toxic, difficult-to-handle, and/or thermally labile reagents. Herein, we report a user-friendly protocol for the synthesis of methyl 4-acetamido-3-(trifluoromethoxy)benzoate using 1-trifluoromethyl-1,2-benziodoxol-3(1H)-one (Togni reagent II). Treating methyl 4-(N-hydroxyacetamido)benzoate (1a) with Togni reagent II in the presence of a catalytic amount of cesium carbonate (Cs2CO3) in chloroform at RT afforded methyl 4-(N-(trifluoromethoxy)acetamido)benzoate (2a). This intermediate was then converted to the final product methyl 4-acetamido-3-(trifluoromethoxy)benzoate (3a) in nitromethane at 120 &#176;C. This procedure is general and can be applied to the synthesis of a broad spectrum of ortho-trifluoromethoxylated aniline derivatives, which could serve as useful synthetic building blocks for the discovery and development of new pharmaceuticals, agrochemicals, and functional materials.

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives

An operationally simple procedure for the synthesis of ortho-trifluoromethoxylated aniline derivatives via a two-step sequence of O-trifluoromethylation of N-aryl-N-hydroxyacetamide followed by thermally induced intramolecular OCF3-migration is reported.

协议的合成<em&gt;邻</em&gt; -trifluoromethoxylated苯胺类化合物

Molecules bearing trifluoromethoxy (OCF3) group often show desired pharmacological and biological properties. However, facile synthesis of ...

Facile Synthesis of Worm-like Micelles by Visible Light Mediated Dispersion Polymerization Using Photoredox Catalyst

Presented herein is a protocol for the facile synthesis of worm-like micelles by visible light mediated dispersion polymerization. This approach begins with the synthesis of a hydrophilic poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) homopolymer using reversible addition-fragmentation chain-transfer (RAFT) polymerization. Under mild visible light irradiation (&#955; = 460 nm, 0.7 mW/cm2), this macro-chain transfer agent (macro-CTA) in the presence of a ruthenium based photoredox catalyst, Ru(bpy)3Cl2 can be chain extended with a second monomer to form a well-defined block copolymer in a process known as Photoinduced Electron Transfer RAFT (PET-RAFT). When PET-RAFT is used to chain extend POEGMA with benzyl methacrylate (BzMA) in ethanol (EtOH), polymeric nanoparticles with different morphologies are formed in situ according to a polymerization-induced self-assembly (PISA) mechanism. Self-assembly into nanoparticles presenting POEGMA chains at the corona and poly(benzyl methacrylate) (PBzMA) chains in the core occurs in situ due to the growing insolubility of the PBzMA block in ethanol. Interestingly, the formation of highly pure worm-like micelles can be readily monitored by observing the onset of a highly viscous gel in situ due to nanoparticle entanglements occurring during the polymerization. This process thereby allows for a more reproducible synthesis of worm-like micelles simply by monitoring the solution viscosity during the course of the polymerization. In addition, the light stimulus can be intermittently applied in an ON/OFF manner demonstrating temporal control over the nanoparticle morphology.

This article describes a process for producing polymeric self-assembled nanoparticles using visible light mediated dispersion polymerization. Using low energy visible light to control the polymerization allows for the reproducible formation of self-assembled worm-like micelles at high solids content.

使用Photoredox催化剂蠕虫状胶束的简便合成可见光介导的分散聚合

Presented herein is a protocol for the facile synthesis of worm-like micelles by visible light mediated dispersion polymerization. This approach begins ...

Synthesis and Testing of Supported Pt-Cu Solid Solution Nanoparticle Catalysts for Propane Dehydrogenation

A convenient method for the synthesis of bimetallic Pt-Cu catalysts and performance tests for propane dehydrogenation and characterization are demonstrated here. The catalyst forms a substitutional solid solution structure, with a small and uniform particle size around 2 nm. This is realized by careful control over the impregnation, calcination, and reduction steps during catalyst preparation and is identified by advanced in situ synchrotron techniques. The catalyst propane dehydrogenation performance continuously improves with increasing Cu:Pt atomic ratio.

A convenient method for the synthesis of 2 nm supported bimetallic nanoparticle Pt-Cu catalysts for propane dehydrogenation is reported here. In situ synchrotron X-ray techniques allow for the determination of the catalyst structure, which is typically unobtainable using laboratory instruments.

用于丙烷脱氢的负载型Pt-Cu固溶体纳米粒子催化剂的合成与测试

A convenient method for the synthesis of bimetallic Pt-Cu catalysts and performance tests for propane dehydrogenation and characterization are ...

Synthesis of Platinum-nickel Nanowires and Optimization for Oxygen Reduction Performance

Platinum-nickel (Pt-Ni) nanowires were developed as fuel cell electrocatalysts, and were optimized for the performance and durability in the oxygen reduction reaction. Spontaneous galvanic displacement was used to deposit Pt layers onto Ni nanowire substrates. The synthesis approach produced catalysts with high specific activities and high Pt surface areas. Hydrogen annealing improved Pt and Ni mixing and specific activity. Acid leaching was used to preferentially remove Ni near the nanowire surface, and oxygen annealing was used to stabilize near-surface Ni, improving durability and minimizing Ni dissolution. These protocols detail the optimization of each post-synthesis processing step, including hydrogen annealing to 250 &#176;C, exposure to 0.1 M nitric acid, and oxygen annealing to 175 &#176;C. Through these steps, Pt-Ni nanowires produced increased activities more than an order of magnitude than Pt nanoparticles, while offering significant durability improvements. The presented protocols are based on Pt-Ni systems in the development of fuel cell catalysts. These techniques have also been used for a variety of metal combinations, and can be applied to develop catalysts for a number of electrochemical processes.

&#160; The protocol describes the synthesis and electrochemical testing of platinum-nickel nanowires. Nanowires were synthesized by the galvanic displacement of a nickel nanowire template. Post-synthesis processing, including hydrogen annealing, acid leaching, and oxygen annealing were used to optimize nanowire performance and durability in the oxygen reduction reaction.

铂镍纳米线的合成及减氧性能优化

Platinum-nickel (Pt-Ni) nanowires were developed as fuel cell electrocatalysts, and were optimized for the performance and durability in the oxygen ...

Synthesis of a Thiol Building Block for the Crystallization of a Semiconducting Gyroidal Metal-sulfur Framework

We present a method for preparing thioester molecules as the masked form of the thiol linkers and their utilization for accessing a semiconducting and porous metal-dithiolene network in the highly ordered single crystalline state. Unlike the highly reactive free-standing thiols, which tend to decompose and complicate the crystallization of metal-thiolate open frameworks, the thioester reacts in situ to provide the thiol species, serving to mitigate the reaction between the mercaptan units and the metal centers, and to improve crystallization consequently. Specifically, the thioester was synthesized in a one-pot procedure: an aromatic bromide (hexabromotriphenylene) reacted with excess sodium thiomethoxide under vigorous conditions to first form the thioether intermediate product. The thioether was then demethylated by the excess thiomethoxide to provide the thiolate anion that was acylated to form the thioester product. The thioester was conveniently purified by standard column chromatography, and then used directly in the framework synthesis, wherein NaOH and ethylenediamine serve to revert in situ the thioester to the thiol linker for assembling the single-crystalline Pb(II)-dithiolene network. Compared with other methods for thiol synthesis (e.g., by cleaving alkyl thioether using sodium metal and liquid ammonia), the thioester synthesis here uses simple conditions and economical reagents. Moreover, the thioester product is stable and can be conveniently handled and stored. More importantly, in contrast to the generic difficulty in accessing crystalline metal-thiolate open frameworks, we demonstrate that using the thioester for in situ formation of the thiol linker greatly improves the crystallinity of the solid-state product. We intend to encourage broader research efforts on the technologically important metal-sulfur frameworks by disclosing the synthetic protocol for the thioester as well as the crystalline framework solid.

Here, we present a one-pot, transition-metal-free synthesis of thiols and thioesters from aromatic halides and sodium thiomethoxide, followed by the preparation of single crystals of a metal-dithiolene network using thiol species generated in situ from the more stable and tractable thioester.

半导体回转金属硫框架结晶的硫醇构建块的合成

We present a method for preparing thioester molecules as the masked form of the thiol linkers and their utilization for accessing a semiconducting and ...

Synthesis of Substrate-Bound Au Nanowires Via an Active Surface Growth Mechanism

Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a challenge, as it requires asymmetric growth of symmetric crystals. Here, we report a distinctive synthesis of substrate-bound Au nanowires. This template-free synthesis employs thiolated ligands and substrate adsorption to achieve the continuous asymmetric deposition of Au in solution at ambient conditions. The thiolated ligand prevented the Au deposition on the exposed surface of the seeds, so the Au deposition only occurs at the interface between the Au seeds and the substrate. The side of the newly deposited Au nanowires is immediately covered with the thiolated ligand, while the bottom facing the substrate remains ligand-free and active for the next round of Au deposition. We further demonstrate that this Au nanowire growth can be induced on various substrates, and different thiolated ligands can be used to regulate the surface chemistry of the nanowires. The diameter of the nanowires can also be controlled with mixed ligands, in which another &#34;bad&#34; ligand could turn on the lateral growth. With the understanding of the mechanism, Au nanowire-based nanostructures can be designed and synthesized.

We report a solution-based method to synthesize substrate-bound Au nanowires. By tuning the molecular ligands used during the synthesis, the Au nanowires can be grown from various substrates with different surface properties. Au nanowire-based nanostructures can also be synthesized by adjusting the reaction parameters.

通过活性表面生长机制合成基片束缚金纳米线

Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a ...

Synthesis and Characterization of 1,2-Dithiolane Modified Self-Assembling Peptides

This report focuses on the synthesis of an N-terminus 1,2-dithiolane modified self-assembling peptide and the characterization of the resulting self-assembled supramolecular structures. The synthetic route takes advantage of solid-phase peptide synthesis with the on-resin coupling of the dithiolane precursor molecule, 3-(acetylthio)-2-(acetylthiomethyl)propanoic acid, and the microwave-assisted thioacetate deprotection of the peptide N-terminus before final cleavage from the resin to yield the 1,2-dithiolane modified peptide. After the high-performance liquid chromatography (HPLC) purification of the 1,2-dithiolane peptide, derived from the nucleating core of the A&#946; peptide associated with Alzheimer&#39;s disease, the peptide is shown to self-assemble into cross-&#946; amyloid fibers. Protocols to characterize the amyloid fibers by Fourier-transform infrared spectroscopy (FT-IR), circular dichroism spectroscopy (CD) and transmission electron microscopy (TEM) are presented. The methods of N-terminal modification with a 1,2-dithiolane moiety to well-characterized self-assembling peptides can now be explored as model systems to develop post-assembly modification strategies and explore dynamic covalent chemistry on supramolecular peptide nanofiber surfaces.

A protocol for the synthesis of a 1,2-dithiolane modified peptide and the characterization of the supramolecular structures resulting from the peptide self-assembly.

12-Dithiolane 改性自组装肽的合成与表征

This report focuses on the synthesis of an N-terminus 1,2-dithiolane modified self-assembling peptide and the characterization of the resulting ...

Synthesis and Bioconjugation of Thiol-Reactive Reagents for the Creation of Site-Selectively Modified Immunoconjugates

Maleimide-bearing bifunctional probes have been employed for decades for the site-selective modification of thiols in biomolecules, especially antibodies. Yet maleimide-based conjugates display limited stability in vivo because the succinimidyl thioether linkage can undergo a retro-Michael reaction. This, of course, can lead to the release of the radioactive payload or its exchange with thiol-bearing biomolecules in circulation. Both of these processes can produce elevated activity concentrations in healthy organs as well as decreased activity concentrations in target tissues, resulting in reduced imaging contrast and lower therapeutic ratios. In 2018, we reported the creation of a modular, stable, and easily accessible phenyloxadiazolyl methyl sulfone reagent &#8212; dubbed &#8216;PODS&#8217; &#8212; as a platform for thiol-based bioconjugations. We have clearly demonstrated that PODS-based site-selective bioconjugations reproducibly and robustly create homogenous, well-defined, highly immunoreactive, and highly stable radioimmunoconjugates. Furthermore, preclinical experiments in murine models of colorectal cancer have shown that these site-selectively labeled radioimmunoconjugates exhibit far superior in vivo performance compared to radiolabeled antibodies synthesized via maleimide-based conjugations. In this protocol, we will describe the four-step synthesis of PODS, the creation of a bifunctional PODS-bearing variant of the ubiquitous chelator DOTA (PODS-DOTA), and the conjugation of PODS-DOTA to the HER2-targeting antibody trastuzumab.

In this protocol, we will describe the synthesis of PODS, a phenyoxadiazolyl methyl sulfone-based reagent for the site-selective attachment of cargos to the thiols of biomolecules, particularly antibodies. In addition, we will describe the synthesis and characterization of a PODS-bearing bifunctional chelator and its conjugation to a model antibody.

硫醇反应试剂的合成与生物共轭作用--用于原位选择性修饰免疫共轭的生成

Maleimide-bearing bifunctional probes have been employed for decades for the site-selective modification of thiols in biomolecules, especially antibodies. ...