Preparation, characterization of Lewis acidic solid acid catalyst Ce-Ag-PW and its catalytic application in biodiesel production via esterification
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摘要: 通过超声浸渍法，经Ce3+和Ag+协同改性磷钨杂多酸（HPW）制备了一种以Lewis酸性活性位为主的固体酸催化剂Ce-Ag-PW。采用X射线衍射（XRD）、傅里叶变换红外光谱（FT-IR）、扫描电镜（SEM）、透射电镜（TEM）、热重（TG）、NH3程序升温脱附（NH3-TPD）、吡啶吸附红外光谱（Py-IR）和X射线光电子能谱（XPS）等表征手段对其物理化学性能进行了表征分析。并以Ce-Ag-PW为经甲醇和油酸酯化反应来合成生物柴油的催化剂，对其的催化活性和稳定性进行了研究。结果表明，Ce-Ag-PW具有高催化活性和稳定性，以其为催化剂，当甲醇与油酸的物质的量比为14: 1，催化剂用量为反应物总质量的2%，反应温度为65 ℃，反应6 h后，油酸的转化率即高达91%。固体酸催化剂在经过4次循环使用后，油酸的转化率仍可达到80.5%。Ce-Ag-PW的高催化活性和稳定性可归因于Ag+可置换HPW中的质子，以及Ce3+的强吸电子作用，使其由Brönsted酸型催化剂转化为以Lewis酸型为主的催化剂。由于Brönsted酸位易与酯化反应过程中生成的水发生水合反应而失活，因而Lewis酸位的形成有助于减少催化剂的失活现象发生。因此，当通过油酸与甲醇酯化反应合成生物柴油时，Ce-Ag-PW是一种具有高催化活性和稳定性的以Lewis酸性活性位为主的固体酸催化剂。
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关键词:
- 生物柴油 /
- 杂多酸 /
- Ce3+和Ag+协同改性 /
- 固体酸 /
- 酯化反应
Abstract: A solid acid catalyst Ce-Ag-PW with Lewis acidic active site as the main active sitewas prepared from the synergistic modification of phosphotungstic heteropoly acid (HPW) by Ce3+ and Ag+ through ultrasonic impregnation. Physicochemical properties of the obtained catalyst were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetry (TG), NH3 temperature programmed desorption (NH3-TPD), pyridine adsorption Fourier-transform infrared (Py-IR)and X-ray photoelectron spectroscopy (XPS).The catalytic activity and stability of Ce-Ag-PW were studied from the biodiesel production via the esterification of oleic acid and methanol. Results showed that Ce-Ag-PW had high catalytic activity and stability. The conversion of oleic acid reached 91% after 6 h with Ce-Ag-PW as catalyst when the molar ratio of methanol to oleic acid was 14:1, the amount of catalyst was 2% of the total mass of the reactant and the reaction temperature was 65 ℃. The conversion of oleic acid could still reach 80.5% after the Ce-Ag-PW catalyst was used for four cycles. The high catalytic activity and stability of Ce-Ag-PW can be attributed to the replacement of the protons in HPW by Ag+ and the strong electron-withdrawing effect exerted by Ce3+, which transforms it from Brönsted acid catalyst to Lewis acid catalyst. Since the Brönsted acid site is easily deactivated due to the hydration reaction between it and the water generated from the esterification reaction, the formation of Lewis acid sites helps reduce catalyst deactivation. Therefore, Ce-Ag-PW solid acid catalyst based on Lewis acidic active sites has high catalytic activity and stability in the catalytic synthesis of biodiesel by the esterification reaction of oleic acid and methanol.-
Keywords:
- biodiesel /
- heteropoly acid /
- synergistic modification of Ce3+ and Ag+ /
- solid acid /
- esterification
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近年来, 企业实行经济承包责任制后, 不少企业出于追求自身的经济效益, 存在“以包代管”和拼设备的短期行为, 如何进行调控, 采取对策措施, 使设备管理维修工作与之相适应, 并沿着设备管理现代化的方向发展, 在此作些探讨。
一 企业设备管理出现的新情况
企业实行经济承包, 出现拼设备短期行为。它表现在投资、生产、分配等各个过程中, 具体反应在设备固定资产的占有、使用和处置等方面的形式和后果, 主要是:
1.设备超负荷运转。有少数企业为超额完成产量、产值、利润、奖金, 在设备使用上不顾设备使用规范、设备能力、检修计划, 经常超负荷运转。个别的企业甚至"驴不死不卸磨", 致使设备性能严重受损, 精度下降, 完好率下降, 甚至造成设备事故, 严重影响了企业生产力的发展。如矿山的装运设备, 施工单位的起重运输设备, 机修企业的机床等设备运动零部件磨损加快, 寿命大为缩短。
2.设备无偿占有、闲置或失修。有些企业忽视设备的投资回收, 将生产设备闲置、积压, 或使用效率低。在生产活动中, 则对设备重使用, 轻管理, 重生产, 轻维修。如有个别承包者说:"反正我们承包了, 你们不要管, 设备工作只要过得去, 完成效益任务就行了。"有的机动科长向主管设备工作的领导汇报工作时, 有的领导说:"我是管生产的, 设备管理工作你们去管。"还有的领导说, "现在生产任务忙, 机床停不下来, 大修不能搞。"还有个别施工企业的仓库闲置着一大堆设备, 无人过问修复, 将大修基金下放给二级单位自提自用。甚至有的设备不提取折旧基金, 有的老、旧设备折旧只提了30%左右, 就申请报废, 要求购买新设备。或将大修设备安排中修, 有的甚至干脆不安排大修, 造成该大修的设备不能大修, 致使设备出现"失修"、"欠债", 设备零部件残缺不齐、漏油、润滑不良。尤其是一些关键生产设备发生"早衰"。如此继续下去, 会给设备恢复性修理造成一堆老大难问题。
3.撤削设备管理机构。由于有的企业经济效益不好, 如果生产任务和利润指标完不成, 认为设备管理维修又不为企业创造产值和利润, 就把设备管理维修置于可有可无的地位。表现在设备维修方式不是贯彻"预防为主"的方针, 而是执行事后维修的方式。将设备管理机构撤削, 把设备管理维修人员调走, 削弱了设备管理维修力量。
4.只重视追求当年的经济效益, 对依靠技术进步, 搞好设备改造更新的决策和管理不够积极, 设备新度系数低, 也缺乏投资的积极性, 损坏了企业持续发展的物质技术基础和后劲。
5.企业内部奖励分配制度不合理。设备维修工人的奖励普遍比生产工人低, 是导致青年维修工人不愿学技术、不安心工作的原因之一。
二 制约拼设备短期行为的对策
为继续深入贯彻国发﹝1987﹞68号《条例》及其实施办法, 做到科学、合理地使用设备, 确保企业经济效益的稳定增长, 制约企业拼设备的短期行为, 现提出对策设想。
1.按《条例》第八条规定, 真正做到把企业设备管理的主要经济、技术考核指标切实列入企业承包经营责任者的责任目标中进行考核。明确具体条款, 辅以相应奖惩办法, 狠抓落实, 克服"以包代管"现象。
2.结合实际, 制定和完善各项管理标准。按照管、用、修结合的原则, 制定和完善包括基本任务、技术经济指标、设备维护保养、安全文明主产、交接班制度、岗位纪律、按程序操作等内容的班组管理、现场管理标准。并相应制订各项专业检查评定细则, 以约束在设备资产上滥用占有、使用和处置的权力。
3.企业实行承包经营时, 在提出企业经营战略目标和实施规划时, 应有设备资产增值和技术进步的规划, 把积累用于技术进步、扩大再生产、改造和更新设备等。
4.强化责任制落实。设备职能部门应坚持科学的综合管理原则。凡是企业内涉及生产设备的各项活动:如对生产设备的规划、投资, 自制设备的制造, 外购设备选型、购置、验收、安装、调试、使用、维修、改造、更新、报废等工作, 设备部门要履行综合管理职责和权力。按照管好、用好、修好、改造好生产设备的权、责, 进一步落实到车间、工段、班组及个人, 以防止设备综合管理被任意割裂和削弱。
5.企业设备管理部门按《江西省全民所有制工业交通企业设备管理检查定级细则》和《江西省全民所有制工业交通设备管理升级标准》, 结合班组管理、现场管理标准进行检查评审考核监督, 兑现承包合同规定的责任。
6.企业内部经济承包责任制要同改革分配制度结合起来。对设备维修工人或工段、班组, 应当同生产操作工人捆在一起实行承包责任目标。应包维修计划、检修质量、状态完好、物耗、工时及信息记载和传递等。应承认维修工人的报酬奖励, 在付出同样劳动量条件下, 至少应等同于同级生产操作工人。在保证完成合同责任目标的前题下, 应允许并组织维修车间或工段对外承担维修改造等技术劳务服务, 收益与企业分成。但为追求对外劳务服务而完不成责任目标者, 要分析原因, 严加防范, 做到奖勤奖优、多劳多得、少劳少得约分配原则, 才能有效鼓励设备维修方面的积极性和约束设备管理方面的短期行为。
7.积极搞活企业闲置设备的调剂和租赁, 提高设备资产利用率。目前我们将企业闲置可供外调机电设备目录已印发至各直管企业及有关单位。凡需购入或租赁目录内设备者, 请与设备所在单位或公司机动处联系。企业机动部门, 应按(88)南色机字第142号文规定负责闲置设备的调剂处理工作。使企业的闲置设备得到及时有偿转让, 用取得的收益投入到在用设备的技术改造和更新上。既可改变设备结构不合理和技术落后面貌, 又可使有的企业获得所需要的经济合算的设备, 节约了资金, 提高了企业设备资产利用率。
8.企业对制止拼设备工作中作出成绩的部门和个人给予表彰奖励。
综上所述, 企业实行经济承包责任制后对企业出现的新情况新问题, 在治理整顿、深化改革中, 应积极推行设备综合管理的方法, 向设备管理现代化方向迈进, 不断完善设备管理体制和管理措施, 才能做到科学、合理地使用设备, 创造出更高的经济效益。
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图 4 （a）HPW和（b）Ce-Ag-PW催化剂的扫描电镜图和（c）Ce-Ag-PW的透射电镜像
Fig 4. SEM image of (a) HPW and (b) Ce-Ag-PW and (c)TEM image of Ce-Ag-PW
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图 9 HPW、Ce-Ag-PW和无催化剂添加时对油酸转化率的影响
Fig 9. Effects of HPW, Ce-Ag-PW and blank test on the conversion of oleic acid
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图 10 Ce-Ag-PW催化剂用量对油酸转化率的影响
Fig 10. Effects of catalyst amount of Ce-Ag-PW on the conversion of oleic acid
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图 11 甲醇与油酸物质的量比对油酸转化率的影响
Fig 11. Effects of molar ratio of oleic acid and methanol on the conversion of oleic acid
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图 12 反应温度对油酸转化率的影响
Fig 12. Effects of reaction temperature on the conversion of oleic acid
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2. 韩双，陈继强，谢钢平，孔重良. 刮削模具对铝合金焊丝表面刮削效果的影响. 江西冶金. 2022(02): 1-5 . 百度学术
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